Cyclic peptide inhibitors of β1 and β2 integrin-mediated adhesion

ABSTRACT

The present invention describes cyclic peptide compounds which modulate integrin mediated adhesion. These compounds can inhibit both β 1  and β 2  mediated adhesion. The invention further relates to therapeutic uses for these compounds in the treatment of adhesion related pathologies.

RELATED APPLICATIONS

The present application is a Continuation-In-Part of International application Ser. No. PCT/US96/10186, filed Jun. 6, 1996 and designating the United States, which in turn claims priority of U.S. application Ser. No. 08/479,411, filed Jun. 7, 1995, now abandoned. The entire contents of each of these applications is hereby incorporated by reference.

RELATED APPLICATIONS

The present application is a Continuation-In-Part of International application Ser. No. PCT/US96/10186, filed Jun. 6, 1996 and designating the United States, which in turn claims priority of U.S. application Ser. No. 08/479,411, filed Jun. 7, 1995, now abandoned. The entire contents of each of these applications is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates to novel cyclic peptides and peptidomimetic compounds which are characterized by cell adhesion modulation activity.

2. Description of Related Art

Vascular endothelial cells form the interface between blood and tissues and control the passage of leukocytes as well as plasma fluid into tissues. A variety of signals generated at the site of inflammation can activate both endothelial cells as well as circulating leukocytes so that they become more adhesive to one another. Activation of endothelium and leukocytes initiates a complex adhesion cascade. This adhesion cascade involves the "tethering" of the leukocytes to the endothelium, after which they "roll" along the endothelial surface and finally strongly adhere and migrate into tissue to perform host defense functions. Several adhesion molecules, belonging to a super gene family consisting of non-covalently associated heterodimeric proteins called integrins, have been identified as being involved in leukocyte-endothelial cell interactions.

The β₂ integrin subfamily includes LFA-1 (CD11a/CD18), Mac-1 (CD11b/CD18, CR3) and p150/95 (CD11c/CD18, CR4). The known ligands for LFA-1 are ICAM-1, ICAM-2 and ICAM-3. The Intracellular Adhesion Molecules (ICAM) are members of the Ig gene superfamily. ICAM-1 is the most ubiquitous of the ICAMs, being expressed in low levels on most peripheral blood leukocytes as well as endothelial cells, fibroblasts and dendritic cells. Cytokine activation of endothelial cells induces a dramatic increase in the expression of ICAM-1 and LFA-1/ICAM-1 interactions which are integral to both lymphocyte adhesion and transmigration through the endothelial barrier; Dustin, M. L. et al, J. Immunol., 137, 245-254 (1986). ICAM-2 is primarily constitutively expressed on endothelial cells; de Fougerolles, A. R. et al, J. Exp. Med., 174, 253-267 (1991), and ICAM-3 is largely found on resting lymphocytes, monocytes and neutrophils; and shows increased expression upon T cell activation; de Fougerolles, A. R. and Springer, T. A., J. Exp. Med., 175, 185-190 (1992).

In addition to its critical role in mediating cellular adhesion, ICAM-1 has also been shown to act as a receptor for a subgroup of rhinoviruses known as the major groups, and soluble ICAM-1 has been shown to act as specific inhibitor of rhinovirus infection; Martin, S. D. et al, Nature, 344, 70-72 (1990). A compound which blocks the interaction of rhinovirus with ICAM-1 may be a powerful pharmacological agent for the prevention and treatment of colds and secondary complications arising from rhinovirus infection.

Members of the β₁ integrin subfamily include α₁ β₁, α₂ β₁, α₃ β₁, α₄ β₁ (VLA-4, CD49d/CD29), α₇ β₁, α₅ β₁ (VLA-5, CD49e/CD29), α₆ β₁, α₈ β₁ and α_(v) β₁ (CD51/CD29). α₄ β₁ binds to both fibronectin and the cytokine inducible molecule on endothelial cells termed vascular cell adhesion molecule (VCAM). α₄ β₁ /VCAM-1 interaction has been shown to be involved with lymphocyte extravasation at sites of chronic inflammation; Elices, M. J. et al, Cell, 60, 577-584 (1990).

An additional member of the "CAM" family of integrin ligands which plays an important role in adhesion is MadCAM (mucosal addressin cell adhesion molecule). This molecule which is primarily expressed on Peyer's Patch HEV and lamina propia vessels, is involved with the homing of lymphoid subsets through interactions with the integrin α₄ β₇ ; Streeter, P. R. et al, Nature, 331, 41 (1988).

Data support important roles for both α₄ β₁ /VCAM and LFA-1/ICAM in inflammation. In vitro data show that antibodies to α₄ block adhesion of lymphocytes to synovial endothelial cells; this adhesion plays a potential role in rheumatoid arthritis (van Dinther-Janssen et al, J. Immunol., 147, 4207 (1991)). Studies in which monoclonal antibodies to α₄ block adhesion of basophils and eosinophils to cytokine activated endothelial cells (Walsh et al, J. Immunol., 146, 3419 (1991); Bochner et al, J. Exp. Med., 173, 1553 (1991)) imply a potential role of α₄ in allergy and asthma. Additionally, in vivo studies have shown that experimental autoimmune encephalomyelitis can be blocked by anti-α₄ monoclonal antibodies (Yednock et al., Nature, 356, 63 (1992)). Migration of leukocytes to an inflammatory site can also be blocked by anti-α₄ monoclonal antibodies (Issekutz et al., J. Immunol., 147, 4178 (1991)). Lastly, in a model of contact hypersensitivity, peptides Gly-Arg-Gly-Asp-Ser-Pro or Glu-Ile-Leu-Asp-Val block ear swelling when administered with sensitized cells into a challenged naive recipient mouse suggesting that α₄ β₁ and possibly α₅ β₁ are involved in this inflammatory response (Ferguson et al., Proc. Natl. Acad. Sci. USA, 88, 8072 (1991)). Compounds which interact with the α₄ β₁ and α₄ β₇ receptors are described in PCT Publication No. WO 94/15958. However, this publication does not describe that any of the compounds described therein inhibit β₁ and β₂ integrin-mediated adhesion.

β₂ integrins and ICAM have been shown to have important roles in graft rejection, ischemia reperfusion, delayed type hypersensitivity, asthma and allergies, inflammatory bowel disease, rheumatoid arthritis and AIDS. Support for the importance of β₂ integrins in mediating inflammatory responses has been demonstrated by the ability of monoclonal antibodies which recognize LFA-1 to block CTL-mediated lysis of target cells, as well as inhibit proliferation of T cells in response to soluble antigens, alloantigens and mitogen.

Several in vivo models have demonstrated the importance of β₂ integrins in delayed-type hypersensitivity. Anti-LFA-1 antibodies have been shown to block the migration of spleen T cells to sites of dermal inflammation, as well as the homing of lymph node and spleen T cells to peripheral and mesenteric lymph node in rats; Issekutz, T. B., J. Immunol., 149, 3394-3402 (1992). Both anti-LFA-1 and anti-ICAM-1 antibodies can reduce ear swelling caused by edema and cell infiltration in association with delayed-type hypersensitivity; Scheynius, A. et al, J. Immunol., 150, 655-663 (1993).

The role of β₂ integrins in allograft rejection has been demonstrated by the ability of anti-ICAM-1 antibodies to control allograft rejection and reperfusion injury in humans; Cosimi, A. B. et al, J. Immunol., 144, 4604-4612 (1990); Haug et al, Transplantation, 55, 766-773 (1993).

Anti-ICAM-1 antibodies have also been shown to attenuate airway eosinophilia, hyper-responsiveness and asthma symptoms in a primate asthma model.

Importantly, it has been demonstrated in vivo that while either anti-α₄ β₁ or anti-LFA-1 antibodies alone demonstrate inhibition of delayed-type hypersensitivity-induced inflammation, a maximal anti-inflammatory response is obtained when anti-α₄ β₁ and anti-LFA-1 antibodies are used in combination; Issekutz, T. B., Amer. J. Path., 143, 1286-1293 (1993).

As both multiple integrin/"CAM" interactions play important roles in the adhesion of leukocytes to endothelium in the inflammatory process, an ideal treatment for inflammatory disease would target both types of integrin/endothelial cell interactions.

SUMMARY OF THE INVENTION

One objective of the present invention is to provide compounds which act to modulate cell adhesion. These compounds are represented by the formula (I): ##STR1## or a pharmaceutically acceptable salt thereof, wherein L¹ is a residue of an amino acid or an amino acid mimetic, having a functional group suitable for the formation of a cyclizing bridge, Z, between L¹ and L². L² is a residue of an amino acid or an amino acid mimetic, having a functional group suitable for the formation of a cyclizing bridge, Z, between L¹ and L². Z is a cyclizing moiety or bond between L¹ and L² ; X⁰ is a residue of an amino acid or an amino acid mimetic and r is an integer of 0 or 1. X¹ is a residue of an amino acid or an amino acid mimetic and m is an integer of 0, 1 or 2. X² is β-Asp or γ-Glu or an ester or an amide derivative formed from the α-carboxyl group of any of the aforementioned groups. X³ is Ser(R⁴), Thr(R⁴), Tyr(R⁴), Ala, Gly, Lys(R⁴), Orn(R⁴), Dpr(R⁴), N-Me-Ala, Aib, Val, Tic, o- or m- halo-Tyr, dihalo-Tyr, p-halo-Phe, dihalo-Phe, Sar, Leu, Ile, Nle or Cys(R⁴) wherein when X³ is Ser(R⁴), Thr(R⁴) or Tyr(R⁴), then R⁴ is a substituent of the side chain hydroxyl group of X³ and is selected from the group consisting of a hydrogen atom, a lower alkyl, a cycloalkyl, a cycloalkyl-lower alkanoyl, an aryl, an arylalkyl, an aryloxycarbonyl, an arylcarbonyl, a heteroaryl-lower alkyl, an arylacetyl, a heterocyclic group, a lower alkanoyl, and arylalkoxycarbonyl, when X³ is Lys(R⁴), Orn(R⁴) or Dpr(R⁴), then R⁴ is a substituent of the side chain terminal amino group of X³ and is selected from the group consisting of a hydrogen atom, a lower alkyl, a cycloalkyl, a lower alkanoyl, an arylalkyl, an arylalkoxycarbonyl, an aryl, an aryloxycarbonyl, an arylcarbonyl, an arylacetyl, and a cycloalkyl-lower alkanoyl, when X³ is Cys(R⁴), then R⁴ is a substituent of the side chain sulfhydryl group of X³ and is selected from the group consisting of a hydrogen atom, lower alkyl, an arylalkyl, an aryl, a cycloalkyl, an aryloxycarbonyl, an arylcarbonyl, an acetamido-lower alkyl, an arylacetyl, a heterocyclic group, lower alkanoyl, an arylalkoxycarbonyl and a cycloalkyl-lower alkanoyl. p is an integer of 0 or 1. X⁴ is Pro, ThioP, Aib, TTC, Asn, TCA, Sar, N-Me-Ala and other N-methylated natural amino acids, Tic or pipecolinic acid (homoproline). q is an integer of 0 or 1. X⁵ is a residue of an amino acid or an amino acid mimetic, n is an integer of 0, 1, 2 or 3. X⁶ is a residue of an amino acid or an amino acid mimetic. s is an integer of 0 or 1. R¹ is a hydrogen atom, Xan, Fmoc, 9-FAc, 9-FCA, 1-FCA, Ac, 2-NaphAc, Ada, 5-Finc, biotinyl, Su, 1-NaphCA, For, 1-NaphAc, PhAc, 1-NaphSO₂, 2-NaphSO₂ or 2-NaphCA, with the proviso that the compound (Fmoc)-Arg-Cys*-(β-Asp)-(ThioP)-Cys* is not included.

Another objective of the present invention is to provide a method for modulating cell adhesion.

Another objective of the present invention is to provide compounds which bind to a cell adhesion molecule or integrin receptor.

Another objective of the present invention is to provide compounds having high potency in modulating specific cell adhesion to integrin receptors, including inhibition of cell adhesion to ligands for both β₁ and β₂ integrins. Thus, in one regard, the present invention includes compounds having an IC₅₀ of less than about 500 μM as established in JY-Endothelial cell and Jurkat-Endothelial cell adhesion assays; in another regard, the invention includes compounds having an IC₅₀ of less than about 100 μM in such assays. The invention also includes methods for obtaining (either in vitro or in vivo), such integrin receptor adhesion inhibition. The compounds of the present invention accomplish strong inhibition at low concentrations, with an IC₅₀ of less than about 500 μM, or alternatively less than about 100 μM.

Another objective of the present invention is to provide compounds having high potency in modulating leukocyte adhesion to endothelial cells. Thus, in one regard, the present invention includes compounds having an IC₅₀ of less than about 200 μM as established in Jurkat-endothelial cell and JY-endothelial cell adhesion assays. Compounds with activity below 100 μM are most preferred, below 150 μM are preferred, below 500 μM are less preferred and above 500 μM least preferred. The invention also includes methods for obtaining (either in vitro or in vivo) such leukocyte receptor adhesion inhibition. The compounds of the present invention accomplish strong inhibition at low concentrations, with an IC₅₀ of less than about 250 μM.

Another objective of the present invention is to provide compounds, pharmaceutical compositions, and methods which may be used in the study, diagnosis, treatment or prevention of diseases and conditions which involve or relate to cell adhesion.

Another objective of the present invention is to provide compounds, pharmaceutical compositions and methods of treatment which may be used to inhibit inflammatory diseases in humans.

Another objective is to provide antibodies made by using the compounds of the invention, such as, but not limited to, antibodies to the compounds and anti-idiotype antibodies to the antibodies disclosed in order to study, diagnose, treat or prevent the above mentioned diseases and conditions which relate to cell adhesion.

Another objective of the present invention is to provide a matrix which can be used to purify proteins, polysaccharides or other compounds which specifically bind to the cyclic peptides of the present invention with high affinity.

The present invention relates to compounds meeting one or more of the above objectives. The compounds have activity as cell adhesion modulators. The novel compounds have been found to modulate cell adhesion by competing, for example, with integrin specific ligands, such as but not limited to, ICAM-1 and VCAM, which are sufficiently inhibited from binding to the leukocyte receptors so as to prevent or reduce cell-cell adhesion. Other uses for the compounds include enhancing cell adhesion to a distinct surface. These useful compounds can function as both cell-adhesion agonists and antagonists.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description, including those compounds exemplified herein, is provided to aid those wishing to practice the present invention. The practice of the present invention is not, however, limited to those exemplified compounds.

Cell adhesion is required for certain normal physiological functions. Yet, there are situations in which cell adhesion is undesirable, or in which modulated cell adhesion is desirable. Many pathologies exist which are related to abnormal cellular adhesion. These include, but are not limited to, rheumatoid arthritis, asthma and allergies, adult respiratory distress syndrome (ARDS), AIDS, cardiovascular disease thrombosis or harmful platelet aggregation, reocclusion following thrombolysis, allograft rejection, reperfusion injury, psoriasis, eczema, contact dermatitis and other skin inflammatory diseases, osteoporosis, osteoarthritis, atherosclerosis, neoplastic disease including metastasis of neoplastic or cancerous growth, treatment of certain eye diseases such as detaching retina, Type I diabetes, multiple sclerosis, systemic lupus erythematosus (SLE), inflammatory and immunoinflammatory conditions including ophthalmic inflammatory conditions and inflammatory bowel disease (e.g., ulcerative colitis and regional enteritis), and other autoimmune diseases.

Altered leukocyte-endothelial interactions are implicated in a number of inflammatory diseases where inappropriate attachment of leukocytes leads to further injury of affected tissue. In vitro results show that such detrimental attachment, in which the leukocyte adheres to endothelial cells or to the extracellular matrix, is mediated by integrin receptors on the leukocyte. In this situation, peptides or other compounds with a binding affinity to integrin receptors are desirable as competitive antagonists and will be useful in treating inflammatory diseases including ARDS, asthma and rheumatoid arthritis.

When insufficient cell adhesion occurs wound healing is undesirably prolonged. A peptide or other compound with suitable affinity for integrin receptors when attached, for example, to a suitably positioned matrix or surface, may be able to promote beneficial cell adhesion and resultant enhancement of wound healing.

Cell adhesion also contributes to metastasis of cancerous tumors. Metastasis has been called "the major underlying cause of death from cancer." (Welch, et al., Intern. J. Cancer, 43, 449 (1989)). EEV-transformed cells have been shown to have increased levels of ICAM-1 expression (Dustin et al., J. Immunol., 137, 245 (1986)). Compounds which can modulate integrin mediated adhesion will be useful in the prevention and treatment of cancer metastases from tumors. These compounds could be included as part of a chemotherapeutic regime against tumors to prevent possible metastases from the primary tumor.

Increased ICAM and VCAM expression can be seen at post-capillary venuole sites. This increased expression has been suggested to play a role in increased risk of arterial blockage from increased cellular adhesion at these sites. Compounds which effect ICAM and VCAM interactions with integrins should be useful in treatment of this type of arterial blockage.

The cellular infiltration associated with graft rejection has been shown to correlate with an increased expression of both ICAM and VCAM expression (Koster and McGregor, J. Exp. Med., 133, 400 (1971); Pelletier et al., J. Exp. Med., 149, 2473 (1992)). Anti-ICAM antibodies are immunosuppressive in monkeys and aid in preventing graft rejection (Wee et al. Trans. Proc., 23, 279 (1991)). Compounds, such as the ones encompassed by this invention are expected to be useful as immunosuppressives for preventing graft rejection. They should also have the advantage over antibodies of being less antigenic in vivo because of their small size and structural design.

The cell adhesion modulation compounds of the present invention are represented in part by amino acid sequence formulas wherein the individual amino acids are represented by their standard three-letter abbreviations, or alternatively, they are represented by one-letter abbreviations as indicated in the following Table of Abbreviations.

    ______________________________________                                         Table of Abbreviations                                                         Amino Acids                                                                    Name              Abbreviations*                                               ______________________________________                                         Glycine           Gly     G                                                    Alanine           Ala     A                                                    Valine            Val     V                                                    Leucine           Leu     L                                                    Isoleucine        Ile     I                                                    Methionine        Met     M                                                    Phenylalanine     Phe     F                                                    Proline           Pro     P                                                    Serine            Ser     S                                                    Threonine         Thr     T                                                    Cysteine          Cys     C                                                    Asparagine        Asn     N                                                    Glutamine         Gln     Q                                                    Tyrosine          Tyr     Y                                                    Tryptophan        Trp     W                                                    Aspartic acid     Asp     D                                                    Glutamic acid     Glu     E                                                    Histidine         His     H                                                    Lysine            Lys     K                                                    Arginine          Arg     R                                                    ______________________________________                                          *Where such abbreviations for amino acids are used without an indication       of enantiomeric structure, either the L or Denantiomers or a mixture of        the L or Denantiomers may suitably be utilized.                          

*Where such abbreviations for amino acids are used without an indication of enantiomeric structure, either the L- or D-enantiomers or a mixture of the L- or D-enantiomers may suitably be utilized.

Amino acids of the peptide backbone are delineated with hyphens; synthetic amino acids, unnatural amino acids, and amino acid mimetics are enclosed in parentheses; the R¹ -R⁵ groups which are attached to the backbone amino acid groups are enclosed in parentheses and are immediately adjacent to the amino acid to which they are attached without an intervening hyphen.

Additional abbreviations used herein include the following:

Ac: Acetyl

Abu: 4-Aminobutyric acid

Acm: Acetamidomethyl

Ada: 1-adamantylacetyl

NH-Ada: 1-adamantylamino

Aib: α-aminoisobutyric acid

β-Ala: β-alanine (3-aminopropionic acid)

β-Asp: β-aspartic acid

AnC: 6-aminocaproic acid

ARDS: Adult Respiratory Distress Syndrome

BCECF-AM: 2', 7'-bis-(2-carboxyethyl)-5-(and -6)-carboxyfluorescein, acetoxymethyl ester, Molecular Probes Cat. No. B-1170

Biotinyl: 3aS-(3aα, 4β, 6aα)!-5- Hexahydro-2-oxo-1H-thieno 3,4-d!imidazol-4-yl!valeryl

Boc: tert-butoxycarbonyl

BSA: bovine serum albumin

Cha: 3-Cyclohexyl-2-aminopropionic acid

CHAc: cyclohexylacetyl

CTL: cytotoxic T-lymphocyte

DCC: dicyclohexylcarbodiimide

DCM: dichloromethane

DIEA: diisopropylethylamine

DMAP: p-dimethylaminopyridine

DMF: dimethylformamide

Dpr: 2,3-diaminopropionic acid

9-FAc: 9-Fluorenylacetyl

1-FCA: 1-Fluorenecarbonyl

9-FCA: 9-Fluorenecarbonyl

5-Finc: 5-Fluoroindole-2-carbonyl

Fm: 9-Fluorenylmethyl

Fmoc: 9-Fluorenylmethoxycarbonyl

FN: fibronectin

For: Formyl

γ-Glu: γ-Glutamic acid

HBSS: Hank's Buffered Saline Solution

HF: hydrofluoric acid

HOAc: acetic acid

HSA: human serum albumin

HUVEC: human umbilical vein endothelial cell

ICAM: intercellular adhesion molecule

IC₅₀ : inhibitory concentration, concentration at which adhesion is inhibited to 50% of control level

IL-1: interleukin 1

LFA-1: Lymphocyte Functional Antigen-1

Me: methyl

MeOH: methanol

N-Me-Ala: N-methylalanine

Nα-Me-Arg: Nα-methylarginine

1-Nal: 1-Naphthylalanine 2-amino-3-(1-naphthyl) propionic acid!

2-Nal: 2-Naphthylalanine 2-amino-3-(2-naphthyl) propionic acid!

1-NaphAc: 1-Naphthylacetyl

2-NaphAc: 2-Naphthylacetyl

1-NaphCA: 1-Naphthalenecarbonyl

2-NaphCA: 2-Naphthalenecarbonyl

1-NaphSO₂ : 1-Naphthalenesulfonyl

2-NaphSO₂ : 2-Naphthalenesulfonyl

Nle: Norleucine

NorArg: Norarginine

(H₂ NC(=NH)NH(CH₂)₂ CH(NH₂)CO₂ H)

NorVal: Norvaline

Orn: Ornithine

PBS: phosphate buffered saline

Pen: penicillamine

(β,β-dimethylcysteine)

PhAc: Phenylacetyl

PMA: phorbol myristate acetate

R.T.: room temperature (about 24° C.)

rTNF: recombinant Tumor Necrosis Factor

Sar: sarcosine

Ser(OMe): O-methylserine

SLE: systemic lupus erythematosus

Su: succinyl

TCA: 3-Thiomorpholinecarboxylic acid (Tetrahydro-1,4-thiazine-3-carboxylic acid)

TFA: trifluoroacetic acid

ThioP: Thioproline(4-Thiazolidinecarboxylic acid)

Thr(OMe): O-methylthreonine

Tic: 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid

TNF: Tumor Necrosis Factor

TTC: Tetrahydro-1,3-thiazine-4-carboxylic acid

Tyr(OMe): O-methyltyrosine

VCAM: vascular cell adhesion molecule

VLA: very late activation antigens

Xan: Xanthene-9-carbonyl

*: indicates participation of the amino acid in the cyclizing linkage

The chemical structures of some of the above compounds and groups are shown below. ##STR2##

A. Description of the Compounds

As discussed above, the present invention is directed to a compound of the formula (I) ##STR3##

In the formula (I), R¹ is a substituent on the α-amino terminal group of the N-terminal amino acid. R¹ is preferably a hydrogen atom, Ada, 1- or 2-NaphAc, 1-NaphSO₂, 2-NaphSO₂, 1-NaphCA, 2-NaphCA, 9-FAc, 1-FCA, 9-FCA, PhAc, Ac, Fmoc, Xan, 5-Finc, biotinyl, Su and For.

In formula (I), X⁰ is an optional group, r is an integer of 0 or 1, and when present, X⁰ is preferably Trp, 1-Nal, 2-Nal, or an aromatic or hydrophobic amino acid, such as Tyr, Leu, Nle, Ile, Val, NorVal and Cha.

In formula (I), X¹ is an optional group, "m" is an integer of 0, 1 or 2 and when present, X¹ is preferably a hydrophobic amino acid or a side chain-protected basic amino acid residue having a side chain terminal amino group with the formula --NHR², where R² is selected from the group consisting of a hydrogen atom, PhAc, 1-NaphAc, 2-NaphAc, Ada, 2-norbornylacetyl, 1-FCA, CHAc and For. Preferred moieties for X¹ include Arg, Lys(R²), Gly, Nα-Me-Arg, Nle, Cha, Orn(R²), Val, NorVal, Dpr(R²), Abu, Leu and Ile.

In formula (I), X² is selected from D- and L-β-Asp and D- and L-γ-Glu and α-carboxyl esters or amides of any of these aforementioned amino acids. The carboxyl peptide linkages of β-Asp and γ-Glu are formed between the side chain carboxyl groups (β-carboxyl or γ-carboxyl) of β-Asp and γ-Glu, respectively, and the α-amino group of the adjacent amino acid. The α-carboxyl group of X² may have the formula --C(O)R³, where R³ is --OR, --NHR or --NRR and where R is a hydrogen atom, a lower alkyl, an aryl, an arylalkyl, a cycloalkyl, a heteroaryl-lower alkyl or a heterocyclic group as appropriate for an amide or ester. More specifically, R may be methyl, Fm, benzyl, cyclohexyl, 1-adamantyl, 2-, 3- or 4-picolyl, 1- or 2-naphthylmethyl or isobutyl. When R³ is --OR and R is a hydrogen atom, --C(O)OH is present. Where R³ is --NHR or --NRR and R is a hydrogen atom, a carboxamide is present. Otherwise, for --NRR each R group may be selected independently of the other R group.

In formula (I), X³ is an optional amino acid residue where "p" is an integer of 0 or 1. When present, preferred amino acids include Ser(R⁴), Thr(R⁴), Tyr(R⁴), Ala, Gly, Lys(R⁴), Orn(R⁴), Dpr(R⁴), N-Me-Ala, Aib, Val, Tic, o- and m-halo-Tyr, dihalo-Tyr, p-halo-Phe, dihalo-Phe, Sar, Leu, Ile, Nle and Cys(R⁴).

In formula (I), X⁴ is an optional amino acid, where "q" is an integer of 0 or 1. When present, preferred amino acids include Pro, ThioP, Aib, Asn, TCA, TTC, Sar, N-Me-Ala, other N-methylated natural amino acids, Tic and pipecolinic acid (homoproline).

In formula (I), X⁵ is optional and "n" is an integer of 0, 1, 2 or 3. In formula (I), X⁶ is optional and "s" is an integer of 0 or 1. Preferred groups for X⁵ and/or X⁶ include a side chain-protected derivative of a basic amino acid residue having a side chain terminal amino group with the formula --NHR⁴ ; a side chain-protected derivative of an acidic amino acid residue having a side chain terminal carboxyl group with the formula --C(O)R⁴, where R⁴ is --OR, --NHR or --NRR; Ser(R⁴), Thr(R⁴), Tyr(R⁴), and R⁴ is a substituent of the hydroxyl group; and Cys(R⁴) and R⁴ is a substituent of the sulfhydryl group. Other preferred groups for X⁵ and/or X⁶ include Ala; Asp(R⁴); Glu(R⁴); Ser(OMe); Thr(OMe); Tyr(OMe); Gly; Abu; AnC; Leu; Val; β-Ala; Lys(R⁴); Dpr(R⁴); Orn(R⁴), Ile and Nle.

On X³, X⁵ or X⁶, R⁴ is a substituent of a terminal amino group of a side chain of a basic amino acid, of a β- or γ-carboxylic group of an acidic amino acid, of a side chain hydroxyl group of Ser, Thr, Tyr or of a hydroxyl containing derivative or analog of Ser, Thr or Tyr or of a sulfhydryl group of Cys or of a sulfhydryl containing derivative or analog of Cys.

When X⁵ and/or X⁶ is a residue of an acidic amino acid or mimetic thereof, the terminus of the side chain may be represented by the formula --C(O)R⁴ and R⁴ is --OR, --NHR or --NRR, wherein R may be a hydrogen atom, a lower alkyl, an aryl, an arylalkyl, a cycloalkyl, a heteroaryl-lower alkyl or a heterocyclic group as is appropriate for an amide or ester functional group. More specifically, R may be benzyl, cyclohexyl, 1- or 2-naphthylmethyl, 2-, 3- or 4-picolyl, 1-adamantyl, Fm, isobutyl or methyl. Where R⁴ is --OR and R is H, the side chain terminal functionality --C(O)OH, is present. Where R⁴ is NHR or NRR and R is H, a carboxamide is present. Otherwise, for --NRR, each R group may be selected independently of the other R group.

When X³, X⁵ or X⁶ is Ser(R⁴), Thr(R⁴) or Tyr(R⁴), R⁴ is a substituent of the hydroxyl group and may be a hydrogen atom, a lower alkyl, a cycloalkyl, a cycloalkyl-lower alkanoyl, an aryl, an arylalkyl, an aryloxycarbonyl, an arylcarbonyl, a heteroaryl-lower alkyl, an arylacetyl, a heterocyclic group, a lower alkanoyl, or an arylalkoxycarbonyl. More specifically, R⁴ may be methyl, benzyl, cyclohexyl, 1- or 2-naphthylmethyl, Fm, 2-, 3- or 4-picolyl or isobutyl. If R⁴ is a hydrogen atom, a hydroxyl side chain is present.

When X³, X⁵ or X⁶ is a residue of a basic amino acid, the terminal group of the side chain may be denoted by the formula --NHR⁴. Preferred groups for R⁴ include a hydrogen atom, lower alkyl, aryl, aryloxycarbonyl, arylcarbonyl, arylacetyl, an arylalkyl, an arylalkoxycarbonyl, a lower alkanoyl, cycloalkyl, and cycloalkyl-lower alkanoyl. More specifically, R⁴ may be cyclohexyl, 1- and 2-naphthylmethyl, Fmoc, 1-FCA, 9-FCA, Ada, Ac and 9-FAc. When R⁴ is a hydrogen atom, an amino terminus of the side chain is present.

When X³, X⁵ or X⁶ is Cys(R⁴) or a sulfhydryl side chain-containing analog or derivative of Cys, R⁴ is a substituent of the sulfhydryl group and is a hydrogen atom, a lower alkyl, an arylalkyl, an aryl, a cycloalkyl, a cycloalkyl-lower alkanoyl, an aryloxycarbonyl, an arylcarbonyl, an acetamido-lower alkyl, an arylacetyl, a heterocyclic group, a lower alkanoyl, or an arylalkoxycarbonyl. More specifically, R⁴ is preferably methyl, benzyl, 1- or 2-naphthylmethyl, cyclohexyl, Fm, Acm, 4-methylbenzyl or Ada. R⁴ is preferably not a hydrogen atom; however, where R⁴ is a hydrogen atom, a sulfhydryl terminal group of the side chain is present.

When X⁵ and/or X⁶ is the C-terminal amino acid residue, the α-carboxyl group may be represented by the formula --C(O)R⁵, where R₅ is --OR, --NHR, or --NRR and R is a hydrogen atom, a lower alkyl, an arylalkyl, an aryl, a cycloalkyl, a heteroaryl-lower alkyl or a heterocyclic group as is appropriate for an amide or ester functional group. More specifically, R may be methyl, Fm, isobutyl, benzyl, cyclohexyl, 1- or 2-naphthylmethyl, 1-adamantyl or 2-, 3- or 4-picolyl. If R₅ is --OR and R is H, an α-carboxyl terminus, --C(O)OH, is present. Where R⁵ is --NHR or --NRR and R is H, a carboxamide is the C-terminus of the peptide. For --NRR, each R group may be selected independently of the other R group.

R¹ -R⁵, where present, are preferably each independently selected so as to enhance the specific activity of the resulting compound and/or to preserve the compound against metabolism in the in vivo environment and to increase the effective half-life of the compound. In this regard, the use of one or more groups for X⁰ -X⁶, particularly at the N-terminal position or in other regions in the compound, promotes the activity of the compound.

In formula (I), a bridge is formed via a cyclizing moiety, Z, between L¹ and L². L¹ and L² are each, or together, residues of amino acids or amino acid mimetics having functional groups suitable for the formation of a cyclizing bridge between L¹ and L².

L¹ and L² are chosen so that each contains a functional group which contributes to the formation of the cyclizing bridge moiety, Z. Thus, Z is formed from functional groups contributed by L¹ and L² and may also contain additional atoms and spacer groups. As is discussed in more detail below, preferred functional groups include thiol, amino and carboxyl groups. Such functional groups may be borne on the side chain of amino acids or amino acid mimetics, or may constitute the α-amino group (in L¹) or terminal-carboxyl group (in L²) thereof.

Preferred moieties for L¹ and L² are Cys, Cys--NH₂ (only for L² and when no X⁵ or X⁶ groups are present), Arg (only for L¹ and when X⁰ or X¹ are absent), Pen, Orn, Lys, Dpr, Gly (only for L¹ and when X⁰ or X¹ are absent), Met, Glu and Asp.

In preferred embodiments of the invention, L¹ and L² are each selected from Cys or Pen. Both Cys and Pen contain a sulfhydryl group and thus, the bridging cyclization can be accomplished by oxidative coupling of the sulfhydryls to form a disulfide bond between residues L¹ and L². In such a case, the cyclizing moiety, Z, is a covalent bond between the two sulfur atoms. This may be depicted generally for compounds wherein, both L¹ and L² are Cys residues as follows: ##STR4## wherein (as with other similar depictions used herein) the functional group portion (here a side chain sulfur atom in both instances) appears in parentheses above the residue having the functional group.

Particularly preferred embodiments are those where L¹ is Cys and L² is Cys.

The cyclizing moiety may also be formed by a hydrocarbon moiety, for example a (poly)methylene bridge moiety of the form --(CH₂)_(y) -- where y is an integer from 1 to 8, preferably 1 to 4. One type of such a bridge is represented below, wherein a cyclic compound is formed with methylene residues, representing Z, between two cysteine side-chain sulfur atoms (representing L¹ and L²). (See, L. Fieser et al., "Reagents for Organic Synthesis", Vol. 1, pp. 356-357, J. Wiley and Sons: (1967); Fieser, J. Amer. Chem. Soc., 96, 1945 (1959)). ##STR5##

In another preferred embodiment, L¹ and L² may be chosen from other natural or synthetic, L- or D-amino acids or amino acid mimetics which provide a side chain or an amino- or carboxyl-terminus suitable as a functional group, for the formation of a cyclizing moiety. For example, L² may be selected from Asp, Glu, or other natural or synthetic amino acids which provide a suitable side chain carboxyl group for cyclic linkage, through formation of an amide bond in a condensation reaction, with an amino group (e.g., an Nα-amino group, or an ω side chain amino group as on, for example, Lys or Orn) on L¹. The cyclizing moiety Z may be a simple amide bond between L¹ and L².

Or, an amino acid residue L² may provide an α-carboxyl group from its carboxyl terminus for amide linkage with either a side chain amino or α-amino group on L¹ ; the direction of the amide linkage may also be reversed where L¹ provides a side chain carboxyl group and L² provides a side chain amino group. Such structures are exemplified as follows: ##STR6## wherein the side chain amino and carbonyl groups of L¹ (Lys) and L² (Asp) are directly bonded (IV); ##STR7## wherein amide bond direction (from side chains of L¹ and L²) is reversed (V); ##STR8## wherein the depicted amino terminus of L¹ is directly bonded to the side chain carboxyl group of Asp (L²) (VI), or the depicted α-carboxyl terminus of L² is directly bonded to the side chain amino group of Lys (L¹) (VII); ##STR9## wherein the depicted a-amino terminus at L¹ is directly bonded to the depicted carboxyl terminus at L², such that an amide bond is formed in the peptide "backbone" of the compound (VIII).

The cyclizing bridge between L¹ and L² may also be formed via a monosulfide (thioether) linkage, as exemplified below. In this regard, see, Palmer et al., in "Peptides--Chemistry, Structure, Biology", pp. 616-618, Rivier & Marshall, Ed., Escom. Leider (1990); and Jung, op. cit., pp. 865-869. ##STR10## If L² is the C-terminal amino acid of the compound and the α-carboxyl group is not utilized in the cyclization of the compound, the α-carboxyl group may be represented as --C(O)R⁵ where R⁵ is --OR, --NHR or --NRR and R is H, a lower alkyl, an aryl, an arylalkyl, a cycloalkyl, a heteroaryl-lower alkyl or a heterocyclic group as is appropriate for an amide or ester functional group. More specifically, R may be methyl, benzyl, cyclohexyl, 1- or 2-naphthylmethyl, 1-adamantyl, Fm, 2-, 3- or 4-picolyl or isobutyl. If R⁵ is --OR and R is H, the α-carboxyl group, --C(O)OH, is present on L². Where R⁵ is --NHR or --NRR and R is H, the carboxamide is present. Otherwise, each R group in --NRR may be selected independently of the other R group.

Other means of cyclization through appropriate choices of L¹, L² and Z will be readily recognized by those of ordinary skill in the art and are included in the scope of the present invention. Synthetic amino acid residues may also be utilized for L¹ or L², as for example, homologues wherein a side chain is lengthened or shortened while still providing the sulfhydryl carboxyl, amino or other reactive functional group for cyclization.

The foregoing discussion of cyclizing moieties (Z) bridging residues (L¹ and L²), substituents, synthetic amino acids, amino acid mimetics, cyclization methods, and the like are applicable to the other structural formulas discussed hereinafter.

The preferable compounds are compounds of the formula (I) wherein L¹ and L² are each or together selected from the group consisting of Cys, Cys--NH₂ (only for L² and when no X⁵ or X⁶ groups are present), Arg (only for L¹ and when X⁰ and X¹ are absent) Pen, Orn, Lys, Dpr, Gly (only for L¹ and when X⁰ and X¹ are absent), Met, Glu and Asp;

Z is selected from a single bond, a lower alkylene or formula: --COCH₂ --;

X⁰ is selected from the group consisting of Trp, 1-Nal, 2-Nal, Tyr, Leu, Nle, Ile, Val, NorVal and Cha;

X¹ is selected from the group consisting of Lys(R²) Gly, Nα-Me-Arg, Nle, Cha, Val, NorVal, Dpr(R²), Arg, Orn(R²), Leu, Ile and Abu;

R² is selected from a hydrogen atom, Ada, 2-norbornylacetyl, 1-FCA, 1-NaphAc, 2-NaphAc, PhAc, For or CHAc;

X² is selected from the group consisting of β-Asp and β-Asp(R³), γ-Glu and γ-Glu(R³) and R³ is --OR, --NHR or --NRR and where R is a hydrogen atom, a lower alkyl, an aryl, an arylalkyl, a cycloalkyl, a heteroaryl-lower alkyl or a heterocyclic group; and

X⁵ and/or X⁶ is selected from the group consisting of Ala; Asp(R⁴) and Glu(R⁴) wherein R⁴ is a substituent of the derivatized side chain terminal carboxyl group and is selected from the group consisting of --OR, --NRR and --NHR where R is selected from the group consisting of a hydrogen atom, a lower alkyl, an aryl, a cycloalkyl, a heteroaryl-lower alkyl, a heterocyclic group and an arylalkyl; Ser(R⁴), Tyr(R⁴) and Thr(R⁴) wherein R⁴ is OR and R is selected from the group consisting of a hydrogen atom, a lower alkyl, a cycloalkyl, an aryl, an arylalkyl, a cycloalkyl-lower alkanoyl, an aryloxycarbonyl, an arylcarbonyl, a heteroaryl-lower alkyl, an arylacetyl, a heterocyclic group, a lower alkanoyl and an arylalkoxycarbonyl; Gly; Abu; Lys(R⁴); Dpr(R⁴) and Orn(R⁴) wherein R⁴ is a substituent of the derivatized side chain terminal amino group and is selected from the group consisting of a hydrogen atom, a lower alkyl, a cycloalkyl, a lower alkanoyl, an arylalkyl, an arylalkoxycarbonyl, an aryl, an aryloxycarbonyl, an arylcarbonyl, a cycloalkyl-lower alkanoyl and an arylacetyl; AnC; Leu; Val; Ile; Nle; β-Ala and Cys(R⁴) wherein R⁴ is a substituent of the derivatized side chain sulfhydryl group expressed as --SR and R is selected from the group consisting of a hydrogen atom, a lower alkyl, a cycloalkyl, an acetamido-lower alkyl, an aryl, an arylalkyl, an aryloxycarbonyl, an arylcarbonyl, an arylacetyl, a heterocyclic group, a lower alkanoyl, an arylalkoxycarbonyl and a cycloalkyl-lower alkanoyl.

Among the above preferable compounds, more preferable ones are those wherein R¹ is selected from the group consisting of hydrogen, Xan, 9-FAc, 9-FCA, 1-FCA, Ac, 2-NaphAc, Ada, 5-Finc, biotinyl, Su, 1-NaphCA, For, 1-NaphAc, PhAc, 1-NaphSO₂, 2-NaphSO₂ and 2-NaphCA.

Among the above more preferable compounds, most preferable ones are those wherein p is an integer of 1.

Other preferable compounds are compounds of the formula (I) wherein

Z is selected from a single bond, a lower alkylene or a group of the formula: --COCH₂ --;

R¹ is selected from hydrogen, 1-FCA, 9-FAc, Ada, 5-Finc, Ac, Biotinyl, 9-FCA, Fmoc, For, 1- or 2-NaphAc, PhAc, 1-NaphSO₂, 2-NaphSO₂, 1- or 2-NaphCA, Xan or Su;

X⁰ is selected from the group consisting of Trp, 1-Nal, 2-Nal, Tyr, Leu, Nle, Ile, Val, NorVal and Cha;

r is an integer of 0 or 1;

X¹ is selected from Arg, Nα-Me-Arg, Lys, Lys(Ada), Lys(1-NaphAC), Lys(PhAc), Lys(For), Lys(2-NaphAc), Orn, Orn(PhAc), Gly, Nle or Cha;

m is an integer of 0 or 1;

L¹ is selected from Cys, Lys, Pen, Orn or Dpr;

X² is selected from β-Asp or β-Asp(αOFm);

X³ is selected from Ser, N-Me-Ala, Gly or Ala;

X⁴ is selected from ThioP, Asn, TCA, Pro, Aib or Tic;

L² is selected from Cys, Cys--NH₂ (only when no X⁵ or X⁶ groups are present), Asp, Pen or Glu;

X⁵ is selected from Ala, Gly, Abu or Lys (Fmoc); and

X⁶ is selected from Asp-(OFm), Asp-(NH-Ada), Ser, Lys, Lys(Fmoc)--NH₂ or Gly.

Among the above preferable compounds, more preferable ones are those wherein

R¹ is selected from a hydrogen atom, 1-FCA, 9-FAc, Ada, 5-Finc, Ac, Biotinyl, 9-FCA, For, 9-FAc, 2-NaphAc, PhAc, 1-NaphSO₂, 2-NaphSO₂, 2-NaphCA or Xan.

Among the above more preferable compounds, most preferable ones are those wherein p is an integer of 1.

Other preferable compounds are compounds of the formula (I) wherein

Z is selected from a single bond, a lower alkylene or a group of the formula: --COCH₂ --;

R¹ is selected from hydrogen, 1-FCA, 9-FAc, Ada, 5-Finc, Ac, Biotinyl, 9-FCA, Fmoc, For, 9-FAc, 2-NaphAc, PhAc, 2-NaphCA or Xan;

X⁰ is Trp;

r is an integer of 0 or 1;

X¹ is selected from Arg, Nα-Me-Arg, Lys, Lys(Ada), Lys(1-NaphAc), Lys(PhAc), Lys(For), Lys(2-NaphAc), Orn, Orn(PhAc), Gly, Nle or Cha;

m is an integer of 0 or 1;

L¹ is selected from Cys, Lys or Pen;

X² is β-Asp;

X³ is selected from Gly or Ala;

X⁴ is selected from ThioP, Asn, Pro or Tic;

L² is selected from Cys, Cys--NH₂ (only when no X⁵ or X⁶ groups are present), Asp or Pen;

X⁵ is selected from Ala, Gly, Abu or Lys(Fmoc); and

X⁶ is selected from Asp-(OFm), Asp-(NH-Ada), Ser, Lys, Lys(Fmoc)--NH₂ or Gly.

Among the above preferable compounds, more preferable ones are those wherein

R¹ is selected from a hydrogen atom, 1-FCA, 9-FAc, Ada, 5-Finc, Ac, Biotinyl, 9-FCA, For, 9-FAc, 2-NaphAc, PhAc, 1-NaphSO₂, 2-NaphSO₂, 2-NaphCA or Xan.

Among the above more preferable compounds, most preferable ones are those wherein p is an integer of 1.

Other preferable compounds are compounds of the formula (I) wherein

Z is a single bond;

R¹ is selected from 1-FCA, 9-FAc, Ac or Xan;

r is an integer of 0;

X¹ is selected from Arg or Lys;

m is an integer of 1;

L¹ is Cys;

X² is β-Asp;

p is an integer of 0;

X⁴ is ThioP;

q is an integer of 1;

L² is selected from Cys or Cys--NH₂ (only when no X⁵ or X⁶ groups are present);

n is an integer of 0; and

s is an integer of 0.

Within a preferred group of structures are the following formulas:

X⁰ in structure I is absent; X¹ is Arg; X² is β-Asp; X³ is absent; X⁴ is ThioP; and X⁵ and X⁶ are absent. In a preferred structure, the cyclizing Z moiety is formed by a disulfide linkage between L¹ and L² cysteine residues and the overall preferred sequence would be Arg-Cys*-(β-Asp)-(ThioP)-Cys* (* denotes residue involved in cyclization of compound).

With the sequence Arg-Cys*-(β-Asp)-(ThioP)-Cys*, R¹ is preferably 1-FCA, 9-FAc, 9-FCA, Xan, For, Ac, Biotinyl, Ada, a hydrogen atom, 5-Finc, PhAc or Su.

Also preferred is a sequence wherein residue X⁰ is absent, residue X¹ is Lys; residue X² is β-Asp; X³ is absent; X⁴ is ThioP; and X⁵ and X⁶ are absent. Thus, the sequence Lys-Cys*-(β-Asp)-(ThioP)-Cys* is also preferred, wherein the cyclizing Z moiety is formed by the disulfide linkage between the cysteine residues. In this preferred structure R¹ is preferably 1-FCA, 9-FCA or 9-FAc or Fmoc.

Another particularly preferred sequence is one wherein X⁰ is absent; X¹ is Arg; X² is β-Asp; X³ is absent; X⁴ is ThioP; and X⁵ is Ala, and n is 2 and X⁶ is absent. Thus, the sequence Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Ala is also preferred, wherein the cyclizing z moiety is formed by a disulfide linkage between the cysteine residues. In this preferred structure, R¹ is preferably 1-FCA, 9-FCA, 2-NaphAc, 1-NaphSO₂, 2-NaphSO₂, 2-NaphCA, Ac or PhAc.

Another particularly preferred sequence is one wherein X⁰ is absent; X¹ is Lys; X² is β-Asp; X³ is absent; X⁴ is ThioP; X⁵ is Ala and n is an integer of 2 and X⁶ is absent. Thus, the sequence Lys-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Ala is also preferred, wherein the cyclization of the peptide occurs through a disulfide linkage formed between the cysteine residues. With this preferred structure, R¹ is preferably 9-FCA and R² is PhAc.

Another particularly preferred sequence is one wherein X⁰ is absent; X¹ is Arg; X² is β-Asp; X³ is absent; X⁴ is ThioP; X⁵ is Ala and X⁶ is Asp. Thus, the sequence Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Asp is also preferred, wherein the cyclization is formed from the disulfide linkage of the two cysteines. With this preferred structure, R¹ is preferably Ac and R⁴ is Ada or Fm.

Also preferred is a sequence wherein residue X⁰ is absent; X¹ is Orn; X² is β-Asp; X³ is absent; X⁴ is ThioP and X⁵ and X⁶ are absent. Thus, the sequence Orn-Cys*-(β-Asp)-(ThioP)-Cys* is also preferred, wherein the sulfhydryl linkages of the two cysteine residues cyclize the peptide. In this structure R¹ is preferably 1-FCA or Fmoc and the side chain terminal amino group of Orn is denoted as NHR², and R² is preferably hydrogen or PhlAc.

Another particularly preferred sequence is one wherein X⁰ is absent; X¹ is Arg; X² is β-Asp; X³ is absent; X⁴ is ThioP; X⁵ is Ala and X⁶ is Ser. Thus, the sequence Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Ser is also preferred, wherein the peptide is cyclized by a disulfide linkage of the cysteine residues. In this structure, R¹ is preferably 1-FCA.

Another particularly preferred sequence is one wherein X⁰ is absent; X¹ is Lys; X² is β-Asp; X³ is absent; X⁴ is TCA; and X⁵ and X⁶ are absent. Thus, the sequence Lys-Cys*-(β-Asp)-(TCA)-Cys* is also preferred, wherein the peptide is cyclized by a disulfide linkage of the cysteine residues. In this structure, R¹ is preferably Fmoc, 9-FAc, 9-FCA or 1-FCA, the ε-amino terminal group of Lys is denoted as NHR² and R² is preferably H, 1-NaphAc, 2-NaphAc or PhAc.

Another particularly preferred sequence is one wherein X⁰ is absent; X¹ is Lys; X² is β-Asp; X³ is absent; X⁴ is Pro; X⁵ and X⁶ are absent. Thus, the sequence Arg-Cys*-(β-Asp)-Pro-Cys* is also preferred, wherein the peptide is cyclized by a disulfide linkage of the cysteine residue. In this structure, R¹ is preferably Fmoc, 9-FAc, 9-FCA or 1-FCA.

Another particularly preferred sequence is one wherein X⁰ is absent; X¹ is Arg; X² is β-Asp; X³ is absent; X⁴ is absent and X⁵ and X⁶ are absent. Thus, the sequence Arg-Cys*-(β-Asp)-Cys* is also preferred, wherein the cyclizing Z moiety is formed by a disulfide linkage between the cysteine residues. In this preferred structure, R¹ is preferably 1-FCA, 9-FCA, 9-FAc or Fmoc.

Another particularly preferred sequence is one wherein X⁰ is absent; X¹ is Arg; X² is β-Asp; X³ is absent; X⁴ is ThioP; X⁵ is Abu and X⁶ is absent. Thus, the sequence Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Abu is also preferred, wherein the cyclization of the peptide occurs through a disulfide linkage formed between the cysteine residues. With this preferred structure, R¹ is preferably 9-FCA, 1-FCA, 9-FAc or Fmoc.

Another particularly preferred sequence is one wherein X⁰ is absent; X¹ is Arg; X² is β-Asp; X³ is absent; X⁴ is ThioP; X⁵ is Ala and X⁶ is absent. Thus, the sequence Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala is also preferred, wherein the sulfhydryl linkages of the two cysteine residues cyclize the peptide. In this structure, R¹ is preferably 1-FCA.

Another particularly preferred sequence is one wherein X⁰ is absent; X¹ is Arg; X² is β-Asp; X³ is absent; X⁴ is ThioP; X⁵ is Gly and n is an integer of 2 and X⁶ is absent. Thus, the sequence Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Gly-Gly is also preferred, wherein the cyclizing Z moiety is formed from the disulfide linkage of the cysteine residues. In this structure, R¹ is preferably 1-FCA, 9-FCA, 9-FAc or Fmoc.

Another particularly preferred sequence is one wherein X⁰ is absent; X¹ is Lys; X² is β-Asp; X³ is absent; X⁴ is ThioP; X⁵ is Ala and X⁶ is Ser. Thus, the sequence Lys-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Ser is also preferred, wherein the cysteine residues are joined by a disulfide linkage. In this structure, R¹ is preferably 1-FCA or 9-FCA, the ε-amino terminal group of Lys is denoted as NHR² and R² is preferably H, 2-NaphAc, 1-NaphAc or PhAc.

Also preferred is a sequence wherein residue X⁰ is absent; X¹ is Arg; X² is β-Asp; X³ is absent and X⁴ is ThioP; X⁵ is Ala and X⁶ is Lys. Thus, the sequence Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Lys is also preferred, wherein the cysteine residues cyclize the compound by forming a disulfide linkage. With this structure R¹ is preferably 2-NaphAc or 9-FAc.

Throughout the present specification and claims, amino acids are those from natural or non-natural sources and are those having at least one amino group and one carboxyl group in a molecule. Those amino acids include amino acids from natural sources or antipodes thereof, D- or L-enantiomeric amino acids, and racemic mixtures of these amino acids.

α-Amino acids or β-amino acids are the preferred examples and may be either one of neutral, acidic, and basic amino acids. As the basic amino acids, there may be mentioned amino acids having plural amino groups or a guanidino group or an imidazolyl group such as arginine, histidine, ornithine, lysine, and the like; as the acidic amino acids, there may be mentioned amino acids having plural carboxyl groups such as glutamic acid, aspartic acid, and the like; and as the neutral amino acids, there may be mentioned amino acids having the same number of amino groups and carboxyl groups such as alanine, isoleucine, leucine, and the like. Further, in the present invention, specific examples of the amino acids which can be used suitably, include glycine, alanine, N-methylalanine, N-α-methylarginine, isoleucine, leucine, valine, norvaline, glutamic acid, methionine, phenylalanine, proline, β-alanine, arginine, norarginine, ornithine, serine, O-methylserine, threonine, O-methylthreonine, asparagine, aspartic acid, β-aspartic acid, glutamine, γ-glutamine, cystine, cysteine, tyrosine, O-methyltyrosine, histidine, tryptophan, lysine, homoarginine, γ-glutamic acid, sarcosine, creatine, homocysteine, norleucine, isoserine, homoserine, norvaline, ornithine, penicillamine, sarcosine, 3-cyclohexyl-2-aminopropionic acid, 2,3-diaminopropionic acid, thioproline, piperidylcarboxylic acid, α,β-diaminobutyric acid, α-aminoisobutyric acid, β-aminobutyric acid, 4-aminobutyric acid, 6-aminocaproic acid, 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid and the like.

Amino acid mimetics are derivatives of the above amino acids. Specific examples of those which can be used suitably, include ester thereof (e.g., a lower alkyl ester, aryl ester), amide thereof (e.g., unsubstituted amide, a cyclohexylamide) or derivative of proline (e.g., thioproline, 3-thiomorpholinecarboxylic acid, tetrahydro-1,3-thiazine-4-carboxylic acid, homoproline, hydroxyproline) and the like.

An aryl group, an aryl moiety in the arylalkyl, aryloxycarbonyl, arylcarbonyl, arylacetyl or arylalkoxycarbonyl is preferably an aromatic hydrocarbocyclic group containing 1 to 4 rings, such as phenyl group, naphthyl group, and the like. A heteroaryl group is preferably an aromatic group containing 1 or 2 rings wherein at least one of the rings contains at least 1, preferably 1 to 3, more preferably 1 or 2 heteroatoms such as N, O or S wherein the remainder of the ring atoms are carbon atoms, wherein each ring contains 4 to 7 ring atoms, with a total of 4 to 11 ring atoms where two fused rings are present. For example, a heteroaryl group is a 5- or 6-membered aromatic heterocyclic group such as thienyl group, furyl group, pyridyl group, pyrazinyl group, pyrimidinyl group, and the like. The above aryl and/or heteroaryl group may have one to three substituents and as the substituent, there may be mentioned a halogen atom, a lower alkyl group and a lower alkoxy group.

As used hereinabove, a lower alkyl group is preferably a C₁ -C₈ alkyl group, more preferably a C₁ -C₅ alkyl group, a lower alkanoyl group is preferably a C₁ -C₉ alkanoyl group, more preferably a C₁ -C₆ alkanoyl group, a lower alkoxy group is preferably a C₁ -C₈ alkoxy group, more preferably a C₁ -C₅ alkoxy group, aryl is preferably a C₆ -C₁₇ aryl group (containing 1 to 4 rings), more preferably a C₆ -C₁₂ aryl group (containing 1 or 2 rings) and most preferably is an aromatic hydrocarbocyclic group containing 1 or 2 rings, such as a phenyl group, naphthyl group and the like, arylalkyl is preferably a C₆ -C₁₇ or C₆ -C₁₂ aryl group (containing 1 or 2 rings) as defined above substituted with a lower alkyl group (as defined above) with the total number of carbon atoms in the arylalkyl group preferably being between 7 and 15, cycloalkyl is preferably a C₃ -C₁₇ cycloalkyl group (containing 1 or 2 cycloalkyl groups), more preferably a C₃ -C₁₂ cycloalkyl group, arylalkoxycarbonyl is preferably an aryl group as defined above substituted with a lower alkoxy group (as defined above) with the total number of carbon atoms in the arylalkoxy group preferably being between 8 and 16 and can include compounds wherein two aryl groups are connected by a cyclic hydrocarbon group, such as Fmoc, and aryloxycarbonyl is preferably an aryl group as defined above having an oxycarbonyl group attached to one of the ring carbon atoms (e.g. Aryl--O--C(O)--), more preferably a C₆ -C₁₃ aryloxycarbonyl (containing 1 or 2 rings), arylcarbonyl is preferably an aryl group as defined above having a carbonyl group attached to one of the ring carbon atoms (e.g. Aryl--C(O)--), more preferably C₇ -C₁₆ arylcarbonyl (containing 1 or 2 rings), arylacetyl is preferably an aryl group as defined above having an acetyl group attached to one of the ring carbon atoms (e.g. Aryl--CH₂ --C(O)--), more preferably a C₈ -C₁₇ arylacetyl group (containing 1 or 2 rings) and heterocyclic is preferably a heterocyclic group containing 1 or 2 rings containing at least 1, preferably 1 to 3, more preferably 1 or 2 heteroatoms such as N, O or S wherein the remainder of the ring atoms are carbon atoms, wherein each ring is saturated or unsaturated and contains 4 to 7 ring atoms, with a total of 4 to 11 ring atoms where two fused rings are present.

2. Therapeutic Utility

In the practice of the therapeutic methods of the present invention, an effective amount of the active compound, including derivatives or salts thereof, or a pharmaceutical composition containing the same in combination with a pharmaceutical carrier or diluent, as described below, is administered via any of the usual and acceptable methods known in the art, either singly or in combination with another compound or compounds of the present invention or other pharmaceutical agents such as immunosuppressants, antihistamines, corticosteroids, and the like. These compounds or compositions can thus be administered orally, sublingually, topically (e.g., on the skin or in the eyes), by inhalation, by suppository, or parenterally (e.g., intramuscularly, intravenously, subcutaneously or intradermally), and in the form of either solid or liquid dosage including tablets, suspensions, and aerosols, as is discussed in more detail below. The administration can be conducted in single unit dosage form with continuous therapy or in single dose therapy ad libitum. A unit dose is defined as 1 to 3000 mg for a human patient.

Useful pharmaceutical carriers for the preparation of the pharmaceutical compositions hereof can be solids, liquids or mixtures thereof; thus, the compositions can take the form of tablets, pills, capsules, powders, enterically coated or other protected formulations (such as binding on ion exchange resins or other carriers, or packaging in lipid or lipoprotein vesicles or adding additional terminal amino acids), sustained release formulations, erodible formulations, implantable devices or components thereof, microsphere formulations, solutions (e.g., ophthalmic drops), suspensions, elixirs, aerosols, and the like.

Water, saline, aqueous dextrose, and glycols are preferred liquid carriers, particularly (when isotonic) for injectable solutions. The carrier can be selected from various oils including those of petroleum, animal, vegetable or synthetic origin, for example, peanut oil, soybean oil, mineral oil, sesame oil, and the like. Suitable pharmaceutical excipients include starch, cellulose, talc, glucose, lactose, sucrose, gelatin, malt, rice, flour, chalk, silica gel, magnesium stearate, sodium stearate, glycerol monostearate, sodium chloride, dried skim milk, glycerol, propylene glycol, water, ethanol, and the like. The compositions may be subjected to conventional pharmaceutical expedients such as sterilization and may contain conventional pharmaceutical additives such as preservatives, stabilizing agents, wetting or emulsifying agents, salts for adjusting osmotic pressure, buffers, and the like. Suitable pharmaceutical carriers and their formulations are described in Martin, "Remington's Pharmaceutical Sciences", 15th Ed.; Mack Publishing Co., Easton (1975); see, e.g., pp. 1405-1412 and pp. 1461-1487. Such compositions will, in general, contain an effective amount of the active compound together with a suitable amount of carrier so as to prepare the proper dosage form for proper administration to the host.

In one preferred embodiment, the therapeutic methods of the present invention are practiced when the relief of symptoms is specifically required or perhaps imminent; in another preferred embodiment, the method hereof is effectively practiced as continuous or prophylactic treatment.

In the practice of the therapeutic methods of the invention, the particular dosage of pharmaceutical composition to be administered to the subject will depend on a variety of considerations including the nature of the disease, the severity thereof, the schedule of administration, the age and physical characteristics of the subject, and so forth. Proper dosages may be established using clinical approaches familiar to the medicinal arts. It is presently believed that dosages in the range of 0.1 to 100 mg of compound per kilogram of subject body weight will be useful, and a range of 1 to 100 mg per kg generally preferred, where administration is by injection or ingestion. Topical dosages may utilize formulations containing generally as low as 0.1 mg of compound per ml of liquid carrier or excipient, with multiple daily applications being appropriate.

The compounds and therapeutic or pharmaceutical compositions of the invention might be useful in the study or treatment of diseases or other conditions which are mediated by the binding of integrin receptors to ligands, including conditions involving inappropriate (e.g., excessive or insufficient) binding of cells to natural or other ligands. Such diseases and conditions might include inflammatory diseases such as rheumatoid arthritis, asthma, allergy conditions, adult respiratory distress syndrome, inflammatory bowel diseases (e.g., ulcerative colitis and regional enteritis) and ophthalmic inflammatory diseases; autoimmune diseases; and cardiovascular disease; prevention of occlusion following thrombolysis; neoplastic disease including metastatic conditions; as well as conditions wherein increased cell binding is desired, as in wound healing or prosthetic implantation situations, as discussed in more detail above.

The compounds of the present invention might find use in the diagnosis of diseases which result from abnormal cell adhesion. For example, excessive adhesion of leukocytes to endothelial cells or to exposed extracellular matrix in blood vessels has been implicated in early stages of atherosclerosis. Thus, a person demonstrating excessive binding of leukocytes to endothelial cells might be at risk for developing occluded arteries. One might detect this risk factor by measuring the binding of a compound of structure I to leukocytes and endothelial cells of the patient thought to be at risk.

Furthermore, the compounds of the present invention might find use in the diagnosis of autoimmune diseases caused by antibodies which bind to cell adhesion molecules or which bind to receptors for cell adhesion molecules. For example, if a disease is caused by antibodies binding to a cell adhesion molecule which is mimicked by a compound of structure I, then a diagnostic test for the presence of such antibodies is easily performed by immunoassay of blood or serum from a patient using a compound of structure I bound to a carrier so as to capture the antibodies. The bound antibody can be detected by the means typical of the art such as a labelled second antibody directed to the Fc portion of human antibodies or using labelled Fc-binding proteins from bacteria (protein A or protein G). In the alternative situation, where the compound of structure I binds to the same receptor as the disease-causing antibody, a competitive immunoassay format can be used. In this format, the compound I is labelled and competition for binding to receptor protein attached to the substrate can be measured.

In addition, derivatives of the present compounds might be useful in the generation of antigens which are prepared by coupling the peptides to a carrier protein. Animals are then immunized with this complex thereby generating antibodies to the peptides. These antibodies will, in some cases, themselves be effective in inhibiting cell adhesion or modulating immune activity by acting as receptors for cell adhesion ligands, or, if anti-idiotypic, by acting to block cellular receptors.

Furthermore, the compounds of the present invention might be used to produce matrices for purifying substances which bind to the compounds of the present invention with high affinity. Such a matrix could be produced, for example, by covalently attaching a compound of the present invention to a derivatized chromatographic support. In one embodiment of this aspect of the invention, a cyclic peptide listed in Table 1 which contains a free amino group can be coupled to a cyanogen bromide activated chromatography resin, such as that available from Pharmacia, (Uppsala, Sweden, Cat. No. 52-1153-00-AK). If necessary, an amino group can be introduced into the desired peptide, either by addition of a lysine residue, or by addition of another amine-containing residue. Alternatively, of course, carbodiimide-activated resin can be used in conjunction with cyclic peptides bearing free carboxyl functions.

The peptide is coupled using the protocol essentially as provided by the manufacturer. The cyclic peptide-derivatized resin can then be used to purify proteins, polysaccharides or the like which may bind the cyclic peptide with high affinity. Such a purification is accomplished by contacting the cyclic peptide-derivatized resin with a sample containing the compound to be affinity purified under conditions which allow formation of the specific complex, washing of the complex bound to the resin with a solution which removes unwanted substances, but leaves the complex intact, and then eluting the substance to be purified by washing the resin with a solution which disrupts the complex.

Compounds of the present invention are expected to be useful in the identification of binding sites of crystalline receptors or ligands. When co-crystallized with the receptor or ligand to be analyzed, these compounds should aid in the identification and structural mapping of relevant binding sites, as well as in the determination of conformational changes which may occur upon binding. Crystallographic analysis will also aid in the selection of compounds of the present invention to be used in pharmaceutical applications.

EXAMPLES

Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods and materials are now described. As set forth above, all publications to which reference is made are incorporated herein by reference.

Example 1 Synthesis and Formation of Compounds

The "backbones," i.e., the peptide-bond linked portions of the cyclic compounds of the invention were generally synthesized using solid phase peptide synthesis as depicted in Table 1, and then cyclized using a procedure in which, where necessary, the appropriate protecting groups were removed prior to cyclization. Other methods for synthesis and cyclization are known in the art and may be employed in the preparation of the cyclic compounds and formulations disclosed herein.

Attachment of N-Boc-S-(4-methylbenzyl)-Cysteine (Boc-Cys-(4-MeBzl) to the chloromethyl polystyrene resin (Merrifield resin) was done in the presence of potassium fluoride (Horiki, Chem. Lett., (#2), 166-168 (1978)).

General Procedures for Synthesis of Cyclic Peptides

Peptide Synthesis: Boc-Cys(4-MeBzl)-polystyrene resin (for C-terminal carboxylic acids) or 4-methylbenzhydrylamine resin (for C-terminal carboxamides) was used for the stepwise assembly of the product peptides using the Boc amino acid procedure in Table 1. Related procedures can be found in the published International Patent Application WO 92/00995, which was previously incorporated by reference. Following coupling of the last amino acid the N-terminal Boc protecting group was removed by mixing the resin with TFA:DCM (1:1) for 20 minutes. Following rinsing in order with DCM (3X), MeOH (2X), DCM (3X) the resin was air dried.

When used in the peptide synthesis, TCA was obtained by the chemical synthesis procedures fully disclosed in the Published International Patent Application WO 94/15958. Those procedures are fully incorporated in their entirety into this application by reference.

Cleavage: The Boc-deprotected peptides on-resin were cleaved by stirring at -5° to 0° C. with a cocktail of distilled anhydrous HF (10 ml/g resin), anisole (1 ml/g resin) and dimethyl sulfide (0.5 ml/g resin). After one hour, the HF was removed under reduced pressure. The cleaved peptide/resin mixture was washed three times with diethyl ether and then extracted with 80% aqueous acetic acid. The combined extracts (100 ml/g or 200 ml/2 g resin) were pooled and carried on to the cyclization step.

Cyclization: The peptides were cyclized through the formation of an amide linkage, a disulfide linkage, a monosulfide linkage or a dithioether linkage, as appropriate.

Purification: The cyclic peptide was purified on a Waters Delta Prep 3000 system (Waters, Milford, Massachusetts) equipped with C₁₈ reverse phase column (15-20 mm, 5×30 cm ID), using a linear gradient of increasing acetonitrile concentration in 1.0% triethylammonium phosphate (TEAP, pH 2.3) as the mobile phase. The appropriate fractions were pooled to give the pure peptide as a phosphate salt. The peptide salt was applied again to the column and eluted with a linear gradient of increasing amounts of acetonitrile in 1.0% aqueous HOAc to afford the desired acetate salt form.

Analysis: The purified peptides were analyzed using a Beckman System 126 (Detector module 166), equipped with a Beckman C₁₈ column (RPC18 Ultrasphere, 5 μm, 4.6×150 mm ID). Elution was performed with buffer A=0.1M sodium phosphate in water, pH 4.4-4.5, buffer B=60% acetonitrile in buffer A, using a linear gradient of buffer B and a flow rate of 1 ml/minute. The gradient was adjusted for each peptide, to provide elution of the peptide near the middle of the gradient.

                  TABLE 1                                                          ______________________________________                                         Schedule for Solid Phase Peptide Synthesis                                     (TFA deprotection/DCC coupling)                                                Step Reagent              Vol* (ml)                                                                               Time (min)                                  ______________________________________                                          1   DCM wash (3×)  20       1/wash                                       2   TFA-DCM (1:1)        20       1                                            3   TFA-DCM (1:1)        20       20                                           4   DCM wash (3×)  20       1/wash                                       5   MeOH wash (2×) 20       1/wash                                       6   DCM wash (3×)  20       1/wash                                       7   5% DIEA-DCM (1:9)    20       1                                            8   5% DIEA-DCM (1:9)    20       5                                            9   DCM wash (4×)  20       1/wash                                      10   Boc AA (2.0 meq.) in DCM .sup.(or DMF) **                                                           120                                                  11   DCC (2.0 meq.) in DCM                                                                               20                                                   12   Recouple if necessary by repeating steps                                       4-11                                                                      13   DCM wash (2×)  20       1/wash                                      14   50% CH.sub.3 OH-DCM wash                                                                            20       1/wash                                      15   MeOH wash (2×) 20       1/wash                                      16   DCM wash (3×)  20       1/wash                                      17   25% (CH3CO)2O-DCM    20       20                                          18   DCM wash (3×)  20       1/wash                                      19   MeOH wash (2×) 20       1/wash                                      20   DCM wash (3×)  20       1/wash                                      ______________________________________                                          *The volume given is for the synthesis using 0.5 meq./gm of growing            peptide chain on two grams of resin.                                           **DMF added where BocAA is insoluble in DCM alone.                       

Procedure A) Synthesis of Amide Linked Side Chain Cyclized Compounds

In this Example, the following compound was synthesized ##STR11##

All natural and synthetic amino acids and derivatives thereof were purchased from BACHEM (Torrance, Calif.). 1-FCA, DCC and diisopropylethylamine and 4-(dimethylamino)-pyridine (DMAP) were obtained from Aldrich (Milwaukee, Wis.). Unless otherwise noted, other reagents were of analytical grade and used without further purification. All residues were linked by the solid phase method using Boc protection.

(1) Synthesis of protected K*(β-D)(ThioP)D* peptide sequence.

Synthesis of the above peptide was performed using, in conjunction, an automated peptide synthesizer (System 990, Beckman Instruments, Inc., Palo Alto, Calif.) and a manual peptide synthesis apparatus (S.C. Glass Tech, Bonica, Calif.). The following amino acids were used in the synthesis: Boc-(ThioP), Boc-β-Asp(α-O-benzyl) and Boc-Lys(N.sup.ε -Fmoc). The N-Boc-L-α-Asp-β-fluoromethyl ester was attached to the hydroxymethyl resin using DCC and DMAP as a catalyst (Fehrentz, J. A. and Castro B., Synthesis, 676-678 (1983)). Boc-L-α-Asp(OFm)OCH₂ -resin (1.0 g, 0.75 mmol) was used as the starting resin. Excess amino acid (2-3 fold) was used for each coupling. The peptide chain was constructed on the Beckman peptide synthesizer using Boc chemistry with the stepwise addition of each amino acid following the standardized cycle similar to that presented in Table 1, with adjustments for scale. 50% TFA in DCM, 5% DIEA in DCM, and 0.5M of DCC in DCM were used as deprotecting, neutralizing, and activating agents, respectively, for each cycle.

(2) Synthesis of N-terminal derivatized peptides

Following the removal of the Boc group from the N-terminal Lys with 50% TFA in DCM, the peptide on resin was washed with MeOH (2×1 min) and DCM (3×1 min) and neutralized with 5% DIEA in DCM (2×1 min). The peptide was then washed with DCM (3×1 min) and reacted with 1-FCA and DCC. Any unreacted amino groups were capped with acetic anhydride in DCM.

(3) General cyclization procedure for formation of the amide bridge.

The peptide was cyclized on the resin by forming an amide linkage between the β-carboxyl group of Asp and the ε-amino group of Lys using the following general procedure.

Filtering was performed between each step: (1) MeOH (2×1 min); (2) DCM (3×1 min); (3) 20% piperidine in DMF, wash for 1 min, and deprotection for 20 min; (4) DMF (2×1 min); (5) MeOH (2×1 min); (6) DCM (3×1 min); (7) BOP reagent (4 equiv.) in DMF (20 ml/gram of resin), stir for 2 min. and add DIEA (2% of DMF volume), stir for 4 hrs (the completion of the cyclization reaction was monitored by the ninhydrin test; if the reaction was judged incomplete at 4 hrs, the reaction was continued until the ninhydrin test was negative); wash with (8) DMF (2×1 min); (9) DCM (2×1 min); (10) MeOH (2×1 min).

The final cyclic compound was removed from the resin by treatment with HF in the presence of anisole for 1 hr at 0° C. After removal of the HF, in vacuo, the residue was washed with diethyl ether and the peptide was extracted from the resin with an aqueous HOAc solution. The aqueous extract was lyophilized to yield the crude peptide.

(4) Purification

The compound was purified using a Waters Delta Prep 3000 system (Waters, Milford, Mass.) equipped with a C₁₈ column, using a linear gradient of increasing acetonitrile concentration in TEAP (pH 2.2 to 2.4) as the mobile phase. The collected fractions of the pure compound were pooled and applied again to the C₁₈ column. This time the sample was eluted with a linear gradient of increasing amounts of acetonitrile in 1.0% aqueous HOAc to convert the phosphate salt form of the peptide to the desired acetate form. The pure peptide fractions were pooled, concentrated in vacuo, redissolved in water and lyophilized to give a white powder.

These synthesis and purification procedures can also be applied to longer cyclic peptide sequences which contain a side chain-side chain cyclizing linkage.

Procedure B) Synthesis of Cyclic Disulfide Compounds

In this example, the following compound was prepared: ##STR12##

All peptides were synthesized by the solid phase method with a Beckman automated peptide synthesizer (System 990, Beckman Instruments, Inc., Palo Alto, Calif.) using Boc chemistry and HF cleavage as discussed above.

Following HF cleavage the peptide was cyclized using a standard iodine cyclization method. (E. Wunsch et al, Int. J. Peptide Res., 32, 368-383 (1988)). After HF cleavage the crude peptide was washed with diethyl ether and then extracted from the resin with 80% aqueous acetic acid in water. The peptide solution was titrated with I₂ -glacial acetic acid (saturated) until the solution turned light brown in color and stirred for one hour at room temperature. The excess iodine was quenched by adding an ascorbic acid-water solution (saturated). The peptide solution was then concentrated under reduced pressure and purified as described for Procedure A, Section 4.

This procedure can also be used for synthesis and purification of longer cyclic peptide compounds which contain a disulfide linkage.

Procedure C) Synthesis of Cyclic Thioether Compounds ##STR13##

1-FCA, bromoacetic acid and DCC were purchased from Aldrich Chemical Company (Milwaukee, Wis.). All natural and synthetic amino acids and derivatives thereof were purchased from BACHEM INC. (Torrance, Calif.). Trifluoroacetic acid was from Halocarbon Co. (New York, N.Y.). Triethylamine was from Fisher Scientific (Fall Lawn, N.J.). Other reagents were obtained from conventional sources and of analytical grade.

The peptide was synthesized by the solid phase method with a Beckman automated peptide synthesizer (System 990, Beckman Instruments, Inc., Palo Alto, Calif.). The following amino acids were used in the synthesis: Boc-Lys(Fmoc), Boc-β-Asp(α-O-Bzl) and Boc-(ThioP). Boc-Cys(4-Me-Bzl)--OCH₂ -polystyrene resin was used for the stepwise assembly of the title peptide, using the Boc amino acid procedure in Table 1. Following capping of the N-terminus with 1-FCA, the Lys N-ε-Fmoc group was removed by treatment with 20% piperidine in DMF. The solution was then stirred for 20 minutes at room temperature and filtered. The resin was washed with DMF. The free Lys side-chain amino group was coupled with bromoacetic acid and after HF cleavage, the peptide was cyclized by forming a mono-sulfide linkage by the general procedure, as described below.

General Cyclization Procedure for Formation of Monosulfide Linkage

The Lys side-chain deprotected peptide was coupled with bromoacetic acid through the use of DCC in DCM. The mixture was stirred for 2 hours at room temperature (completion of the coupling reaction was monitored by the ninhydrin test). The resin was washed with DCM (3×1 min), MeOH (2×1 min) and DCM (3×1 min).

The bromoacetyl peptide was removed from the resin by treatment with HF in the presence of anisole (1 ml/g resin) and DMS (0.5 ml/g resin) for 1 hr. at 0° C. The HF was removed under reduced pressure. The cleaved mixture was washed three times with diethyl ether and the peptide was extracted into aqueous acetic acid. This bromoacetyl peptide is unstable, and the cyclization to form the monosulfide bridge immediately followed the HF cleavage.

Dilute NH₄ OH solution was added to the crude peptide extract. The pH was adjusted to 8-9, and the solution was stirred for one hour at room temperature, (completion of the cyclization was monitored by HPLC and the Ellman test). The crude cyclized peptide was purified as described for Procedure A, Section 4.

Procedure D) Synthesis of Cyclic Dithioether

In this example, the following compound was prepared: ##STR14##

1-Fluorenecarboxylic acid, dibromoethane, and DCC were purchased from Aldrich Chemical Company (Milwaukee, Wis.). All amino acids, amino acid derivatives and analogs were purchased from BACHEM INC. (Torrance, Calif.). Trifluoroacetic acid was from Halocarbon Co. (New York, N.Y.). Triethylamine was from Fisher Scientific (Fall Lawn, N.J.). Other reagents were obtained from conventional sources and were of analytical grade.

The peptide was synthesized by the solid phase method with a Beckman automated peptide synthesizer (System 990, Beckman Instruments, Inc., Palo Alto, Cal.). N-Boc-S-9-Fluorenylmethyl-L-Cysteine was attached to the hydroxymethyl resin using DCC and DMAP as a catalyst. The following amino acids were used in the synthesis: Boc-Arg(Tos), Boc-β-Asp(α-O-Bzl) and Boc-(ThioP) . Boc-Cys (Fm)--OCH₂ -polystyrene resin was used for the stepwise assembly of the peptide following the Boc amino acid procedure in Table 1. Following reaction of the peptide with 1-Fluorenecarboxylic acid at the α-N-terminal Arg, the two Fm-groups were removed from the Cys-side chains by 20% piperidine in DMF, as discussed above. The peptide was cyclized to form the dithioether linkage on the resin by the general procedure below.

General cyclization procedure for formation of dithioether linkage

The dithioether linkage (--S--(CH₂)n--S--) was synthesized while the peptide was bound on the resin. After removing the Fm-groups from the Cys-side chains, the dithioether linkage was formed by adding dibromoethane (3 equivalents) and DIEA in DMF. The pH was adjusted to 8-9, and the solution was stirred for 2 to 4 hours at room temperature, (completion of the cyclization was monitored by HPLC and the Ellman test). The peptide was then washed with DMF (2×1 min), DCM (3×1 min), MeOH (2×1 min) and DCM (3×1 min).

The cyclic peptide was removed from the resin by treatment with HF in the presence of anisole for 1 hr. at 0° C. After removal of the HF, in vacuo, the residue was washed with diethyl ether and the peptide was extracted into an aqueous acetic acid solution. The aqueous extract was lyophilized to yield the crude peptide. The crude peptide was purified as described for Procedure A, Section 4.

                                      TABLE 2                                      __________________________________________________________________________     Analytical data                                                                compounds:                     Cyclization                                     #  Name                        Procedure                                                                            Purity                                                                              MS                                   __________________________________________________________________________     1) Arg-Cys*-(β-Asp)-(ThioP)-Cys*                                                                         B     74.5                                      2) (9-FAc)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*                                                                 B     97.2 815                                  3) (Ada)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*                                                                   B     93.6 785                                  4) (1-FCA)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*                                                                 B     98.0 801                                  5) Trp-Arg-Cys*-(β-Asp)-(ThioP)-Cys*                                                                     B     90.7                                      6) (5-Finc)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*                                                                B     97.1 770                                  7) (9-FAc)-Arg-Cys*-(β-Asp)-Asn-Cys*                                                                     B     100                                       8) (Ac)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-NH.sub.2                                                           B     99.2 650                                  9) (Ac)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*                                                                    B     99.9 651                                  10)                                                                               (Biotinyl)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*                                                              B     99.4                                      11)                                                                               (1-FCA)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-NH.sub.2                                                        B     100                                       12)                                                                               (1-FCA)-Gly-Cys*-(β-Asp)-(ThioP)-Cys*                                                                 B     99.5                                      13)                                                                               (1-FCA)-Lys-Cys*-(β-Asp)-(ThioP)-Cys*                                                                 B     100  773                                  14)                                                                               (Nα-Me-Arg)-Cys*-(β-Asp)-(ThioP)-Cys*                                                           B     100                                       15)                                                                               (1-FCA)-Arg-Cys*-(β-Asp)-(N-Me-Ala)-Cys*                                                              B     94.1                                      16)                                                                                ##STR15##                  D     96.7                                      17)                                                                               (1-FCA)-(D-Arg)-Cys*-(β-Asp)-(ThioP)-Cys*                                                             B     99.7                                      18)                                                                                ##STR16##                  D     98.7                                      19)                                                                               (9-FCA)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*                                                                 B     100                                       20)                                                                               (1-FCA)-Cys*-(β-Asp)-(ThioP)-Cys*                                                                     B     99.4                                      21)                                                                               (Fmoc)-Lys(Ada)-Cys*-(β-Asp)-(ThioP)-Cys*                                                             B     96.4                                      22)                                                                               (Fmoc)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*                                                                  B     89.5 830                                  23)                                                                               (For)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*                                                                   B     88.2                                      24)                                                                               (For)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-NH.sub.2                                                          B     61.4                                      25)                                                                               (1-FCA)-Arg-Cys*-(β-Asp)-Ser-(ThioP)-Cys*                                                             B     99.9                                      26)                                                                               (1-FCA)-(Nle)-Cys*-(β-Asp)-(ThioP)-Cys*                                                               B     100                                       27)                                                                               (1-FCA)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Ala                                                         B     98.6                                      28)                                                                               (1-FCA)-Arg-Cys*-(β-Asp)-Ser-(ThioP)-Cys*-Ala-Ala                                                     B     100                                       29)                                                                               Lys(1-NaphAc)-Cys*-(β-Asp)-(ThioP)-Cys*                                                               B     99.1                                      30)                                                                               (1-FCA)-(Cha)-Cys*-(β-Asp)-(ThioP)-Cys*                                                               B     98.3                                      31)                                                                               (Fmoc)-Lys(PhAc)-Cys*-(β-Asp)-(ThioP)-Cys*                                                            B     82.8                                      32)                                                                               (1-FCA)-Lys(For)-Cys*-(β-Asp)-(ThioP)-Cys*                                                            B     96.2                                      33)                                                                               (Fmoc)-Lys(1-NaphAc)-Cys*-(β-Asp)-(ThioP)-Cys*                                                        B     99.7                                      34)                                                                               (Fmoc)-Lys(2-NaphAc)-Cys*-(β-Asp)-(ThioP)-Cys*                                                        B     99.6                                      35)                                                                               (1-FCA)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Ala-Asp-(OFm)                                               B     70.8                                      36)                                                                               (Ac)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Ala                                                            B     98.5                                      37)                                                                               (Ac)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Asp-(OFm)                                                      B     99.4                                      38)                                                                               (Ac)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Asp-(NH-Ada)                                                   B     98.4                                      39)                                                                               (1-FCA)-Arg-Cys*-(β-Asp)-Gly-(ThioP)-Cys*                                                             B     99.2                                      40)                                                                               (Fmoc)-Lys-Cys*-(β-Asp)-(ThioP)-Cys*                                                                  B     99.1 803                                  41)                                                                               (Ac)-Cys*-(β-Asp)-(ThioP)-Cys*-Lys(Fmoc)-Gly                                                          B     69.0 902                                  42)                                                                               (1-FCA)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Ala-Ala                                                     B     90.8 773                                  43)                                                                               (Fmoc)-Orn-Cys*-(β-Asp)-(ThioP)-Cys*                                                                  B     96.2                                      44)                                                                               (Fmoc)-Orn(PhAc)-Cys*-(β-Asp)-(ThioP)-Cys*                                                            B     72.0                                      45)                                                                               (1-FCA)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Ser                                                         B     97.0 959                                  46)                                                                               (9-FAc)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Ala                                                         B     88.5                                      47)                                                                               (2-NaphAc)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Ala                                                      B     99.5                                      48)                                                                               (PhAc)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Ala                                                          B     98.4                                      49)                                                                               (1-NaphSO.sub.2)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Ala                                                B     99.4                                      50)                                                                               (2-NaphSO.sub.2)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Ala                                                B     83.3                                      51)                                                                               (1-FCA)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala                                                             B     100                                       52)                                                                               (1-FCA)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Gly-Gly                                                         B     76.8                                      53)                                                                               (2-NaphCA)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Ala                                                      B     96.7                                      54)                                                                               (9-FAc)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Lys                                                         B     100                                       55)                                                                               (2-NaphAc)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Lys                                                      B     88.6                                      56)                                                                               (2-NaphAc)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Lys(Fmoc)-NH.sub.2                                       B     86.9                                      57)                                                                               (2-NaphAc)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-(Abu)-Lys                                                    B     99.1                                      58)                                                                               (9-FCA)-Lys(PhAc)-Cys*-(β-Asp)-(ThioP)-Cys*                                                           B     89.6                                      59)                                                                               (1-FCA)-Lys(PhAc)-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Ser                                                   B     96.5                                      60)                                                                               (1-FCA)-Lys(PhAc)-Cys*-(β-Asp)-(ThioP)-Cys*                                                           B                                               61)                                                                               (9-FCA)-Lys-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Ala                                                         B     99.8                                      62)                                                                               (1-FCA)-Arg-Cys*-(β-Asp)-(TCA)-Cys*                                                                   B     100                                       63)                                                                               (2-NaphAc)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*                                                              B     100                                       64)                                                                               (9-FAc)-Lys-Cys*-(β-Asp)-(ThioP)-Cys*                                                                 B     92.4                                      65)                                                                               (9-FAc)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-(Abu)-Lys                                                       B     98.4                                      66)                                                                               (9-FCA)-Lys(PhAc)-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Ala                                                   B     99.3                                      67)                                                                               (1-FCA)-Lys*-(β-Asp)-(ThioP)-Asp*                                                                     A     95.5                                      68)                                                                                ##STR17##                  C     100                                       69)                                                                               (9-FAc)-Lys(PhAc)-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Ser                                                   B     88.2                                      70)                                                                               (Xan)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*                                                                   B     94.8                                      71)                                                                               (PhAc)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*                                                                  B     100                                       72)                                                                               (Fmoc)-Arg-Cys*-(β-Asp)-Pro-Cys*                                                                      B     99.0 813                                  73)                                                                               (Fmoc)-Arg-Cys*-(β-Asp)-(Aib)-Cys*                                                                    B     99.9 801                                  74)                                                                               (Fmoc)-Arg-Cys*-(β-Asp)-Ala-Cys*                                                                      B     91.9 787                                  75)                                                                               (Fmoc)-Arg-Cys*-(β-Asp)-(N-Me-Ala)-Cys*                                                               B     99.0 801                                  76)                                                                               (Fmoc)-Arg-Cys*-(β-Asp)-(Tic)-Cys*                                                                    B     99.9 875                                  77)                                                                               (Fmoc)-Arg-Cys*-(β-Asp)-Pro-Cys*-NH.sub.2                                                             B     99.9 812                                  78)                                                                               (Fmoc)-Arg-Cys*-(β-Asp)-(N-Me-Ala)-Cys*-NH.sub.2                                                      B     98.0 800                                  79)                                                                               (Fmoc)-Arg-Cys*-(D-β-Asp)-(ThioP)-Cys*                                                                B     96.0 831                                  80)                                                                               (Fmoc)-Arg-Cys*-(β-Asp)-(ThioP)-(D-Cys*)                                                              B     99.0 831                                  81)                                                                               (Fmoc)-Arg-Cys*-(β-Asp)-(D-Pro)-Cys*                                                                  B     99.9 813                                  82)                                                                               (Fmoc)-Arg-(Pen)*-(β-Asp)-(ThioP)-Cys*                                                                B     98.0 859                                  83)                                                                               (Fmoc)-Arg-Cys*-(β-Asp)-(ThioP)-(Pen)*                                                                B     99.0 858                                  84)                                                                               (Fmoc)-Arg-(D-Pen)-*-(β-Asp)-(ThioP)-(D-Pen)*                                                         B     99.0 887                                  85)                                                                               (Fmoc)-Arg-Cys*-(β-Asp)-Cys*                                                                          B     96.0 716                                  86)                                                                               (Ac)-Cys*-((β-Asp)(OFin))-(ThioP)-Cys*                                                                B     99.0 673                                  __________________________________________________________________________      *denotes residue utilized in the cyclization of the compound                   Amino acids of the peptide backbone are delineated with hyphens; syntheti      amino acids, unnatural amino acids, and amino acid mimetics are enclosed       in parentheses; the R.sup.1 -R.sup.5 groups which are attached to the          backbone amino acid groups are enclosed in parentheses and are immediatel      adjacent to the amino acid to which it is attached without an intervening      hyphen.                                                                        In Table 2, the amino acid without an indication of enantiomeric structur      means Lenantiomer.                                                       

Example 2 Cell Adhesion Inhibition Assays

Jurkat-Endothelial Cell Adhesion Assay

The following assay established the activity of the present compounds in inhibiting β₁ -mediated cell adhesion in a representative in vitro system. This assay measured the adhesive interactions of a T-cell line, Jurkat, known to express high levels of α₄ β₁, to endothelial cell monolayers in the presence of representative test compounds of the present invention. The test compounds were added in increasing concentrations to T-cells and then the T-cell/compound mixture was added to IL-1 stimulated endothelial cell monolayers. The plates were incubated, washed and the percentage of attached cells was quantitated. The present assay directly demonstrated the cell adhesion inhibitory activity and adhesion modulatory activity of the present compounds.

Human umbilical vein endothelial cells (HUVEC) were purchased from Clonetics (San Diego, Calif.) at passage number 2. The cells were grown on 0.5% porcine skin gelatin pre-coated flasks (Sigma, St. Louis, Mo.) in EGM-UV media (Clonetics, San Diego, Calif.) supplemented with 10% fetal bovine serum. Cells were re-fed every 2-3 days, reaching confluence by day 4 to 6. The cells were monitored for factor VIII antigen and our results showed that at passage 12, the cells are positive for this antigen. The endothelial cells were not used following passage 7.

The T-cell line Jurkat was obtained from American Type Culture Collection and cultured in RPMI media containing 10% fetal calf serum. The cells were washed twice in Hank's buffered saline solution (HBSS) and resuspended in Dulbecco's Minimal Eagle's Media (DMEM) containing 2.5 mg/ml Human Serum Albumin (HSA). Jurkat cells (1×10⁶ cells/ml) were stained with 10 ng/ml BCECF-AM (Molecular Probes, Eugene, Oreg.) in HBSS without phenol red. The cells were loaded with the BCECF-AM for 60 minutes in the dark at 37° C., washed 2 times, and resuspended in DMEM-HSA solution.

Confluent endothelial monolayers, grown in 96-well tissue culture plates, were stimulated for 4 hours at 37° C. with 0.1 ng/ml (50 U/ml) recombinant IL-1 (Amgen, Thousand Oaks, Calif.). Following this incubation, the monolayers were washed twice with HBSS and 0.1 ml of DMEM-HSA solution was added. Jurkat cells (5×10⁵ cells) were combined with the appropriate concentration of peptide and 0.1 ml of the Jurkat cell-peptide mixture was added to the endothelial cell monolayers. Generally, 250, 50, 10 and 2 μM peptide concentrations were tested. With several potent peptides the IC₅₀ was determined by testing the peptides at 50, 10, 2 and 0.4 μM. The plates were placed on ice for 5 minutes to allow for Jurkat cell settling and the plates were incubated at 37° C. for 20 minutes. Following this incubation, the monolayers were washed twice with PBS containing 1 mM calcium chloride and 1 mM magnesium chloride and the plates were read using a Millipore Cytofluor 2300 (Marlboro, Mass.). Fluorescence in each well was measured as Arbitrary Fluorescence Units and percent adhesion in the absence of peptide was adjusted to 100% and the % adhesion in the presence of peptides was calculated. Monolayers were also fixed in 3% paraformaldehyde and evaluated microscopically to verify the adhesion.

The JY-Endothelial Cell Assay

The following assay established the activity of the present compounds in inhibiting cell adhesion through β₂ integrins in a representative in vitro system. The present assay directly demonstrated the anti-β₂ adhesion activity and adhesion modulatory activity of the present compounds.

The human B cell line, JY, was cultured in RPMI media containing 10% fetal calf serum at 37° C., in a humidified CO₂ atmosphere. Endothelial cells were grown to confluency in 96-well micro-titer assay plates, as in the Jurkat-EC assay. Before the assay, the endothelial cells were stimulated with 50 U/ml rTNF for 18-24 hours at 37° C. JY cells were loaded with the fluorescent dye indicator BCECF-AM as follows: JY cells were washed twice with HBSS and cells were resuspended in HBSS at 5×10⁶ cells/ml; BCECF-AM (Molecular Probes), stock concentration=1 mg/ml in DMSO, was added to the JY cells to a final concentration of 2 μg/ml; cells were incubated in the dark at 37° C. for 30-45 minutes; washed twice with HBSS and used in the assay.

The compounds presented in this invention were typically dissolved in 2.5 mg HSA/ml DME at four times the assay concentration and Ph adjusted with 7.5% Na bicarbonate, as needed.

TNF-stimulated HUVEC were washed twice with HBSS (at room temp). 50 μl of cold HSA-DME was added to each well and the plate transferred to ice. While on ice, the following components were added to the wells in the indicated order:

1) 50 μl test compound

2) 50 μl BCECF-labelled JY cells

3) 50 μl PMA (50 ng/ml)

The assay plates were then typically incubated for 30 min at 37° C. and washed four times with PBS containing Mg²⁺ and Ca²⁺ (room temp). 100 μl of PBS containing Mg²⁺ and Ca²⁺ were added to each well and the fluorescence from the adherent BCECF-labelled cells was analyzed using a fluorescence plate reader. Controls were included which were -TNF/+PMA, +TNF/-PMA, +TNF/+PMA (without compound) and either anti-LFAα or anti-LFAβ supernatants.

Results of Jurkat-Endothelial Cell Adhesion

The above-described adhesion assay yielded the following results for the inhibition of Jurkat cell adhesion to IL-1 stimulated endothelial cells.

Results of JY-Endothelial Cell Adhesion

The above-described adhesion assay yielded the following results for the inhibition of JY cell adhesion to TNF stimulated endothelial cells.

Thus an objective of the present invention is to provide compounds having extraordinarily high potencies in modulating cell adhesion to VCAM and ICAM through β₁ and β₂ integrins, respectively, including but not limited to inhibition of T-cell adhesion to endothelial cells. The exact receptors involved in this interaction and the specific receptors targeted by the test compounds include, but are not limited to, α₄ β₁, α₄ β₇, α_(V) β₁, α_(L) β₂, and α_(M) β₂.

The following table 3 shows results from three of the above assays using data from various compounds of the present invention.

                                      TABLE 3                                      __________________________________________________________________________     compounds:                        IC.sub.50.sup.1 for adhesion                                                   inhibition.sup.2                             #     Name                        JY-EC  Jurk-EC                               __________________________________________________________________________     2)    (9-FAc)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*                                                                 141    3                                     4)    (1-FCA)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*                                                                 61     0.3                                   8)    (Ac)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-NH.sub.2                                                           169    84                                    11)   (1-FCA)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-NH.sub.2                                                        175                                          13)   (1-FCA)-Lys-Cys*-(β-Asp)-(ThioP)-Cys*                                                                 68     <2                                    19)   (9-FCA)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*                                                                 54                                           22)   (Fmoc)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-NH.sub.2                                                         52                                           24)   (For)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-NH.sub.2                                                          393                                          26)   (1-FCA)-(Nle)-Cys*-(β-Asp)-(ThioP)-Cys*                                                               218                                          27)   (1-FCA)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Ala                                                         51                                           31)   (Fmoc)-Lys(PhAc)-Cys*-(β-Asp)-(ThioP)-Cys*                                                                   87                                    33)   (Fmoc)-Lys(1-NaphAc)-Cys*-(β-Asp)-(ThioP)-Cys*                                                               88                                    34)   (Fmoc)-Lys(2-NaphAc)-Cys*-(β-Asp)-(ThioP)-Cys*                                                               148                                   35)   (1-FCA)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Ala-Asp-(OFm)                                                      267                                   37)   (Ac)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Asp-(OFm)                                                             106                                   40)   (Fmoc)-Lys-Cys*-(β-Asp)-(ThioP)-Cys*                                                                         436                                   41)   (Ac)-Cys*-(β-Asp)-(ThioP)-Cys*-Lys-(Fmoc)-Gly                                                                78                                    43)   (Fmoc)-Orn-Cys*-(β-Asp)-(ThioP)-Cys*                                                                         165                                   44)   (Fmoc)-Orn-(PhAc)-Cys*-(β-Asp)-(ThioP)-Cys*                                                                  81                                    45)   (1-FCA)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Ser                                                                63                                    46)   (9-FAc)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Ala                                                                56                                    47)   (2-NaphAc)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Ala                                                             79                                    49)   (1-NaphSO.sub.2)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Ala                                                       239                                   50)   (2-NaphSO.sub.2)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Ala                                                       194                                   51)   (1-FCA)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala                                                                    101                                   52)   (1-FCA)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Gly-Gly                                                                64                                    53)   (2-NaphCA)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Ala                                                             387                                   54)   (9-FAc)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Lys                                                                197                                   55)   (2-NaphAc)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Lys                                                             251                                   56)   (2-NaphAc)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Lys(Fmoc)-NH.sub.2           5                                  245                                   58)   (9-FCA)-Lys(PhAc)-Cys*-(β-Asp)-(ThioP)-Cys*                                                                  70                                    59)   (1-FCA)-Lys(PhAc)-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Ser                                                          63                                    60)   (1-FCA)-Lys(PhAc)-Cys*-(β-Asp)-(ThioP)-Cys*                                                                  71                                    61)   (9-FCA)-Lys-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Ala                                                         117                                          64)   (9-FAc)-Lys-Cys*-(β-Asp)-(ThioP)-Cys*                                                                 133                                          65)   (9-FAc)-Lys-Cys*-(β-Asp)-(ThioP)-Cys*-(Abu)-Lys                                                       353                                          68)                                                                                   ##STR18##                  190                                          69)   (9-FAc)-Lys(PhAc)-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Ser                                                   94                                           70)   (Xan)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*                                                                   92     10                                    72)   (Fmoc)-Arg-Cys*-(β-Asp)-Pro-Cys*                                                                      60                                           74)   (Fmoc)-Arg-Cys*-(β-Asp)-Ala-Cys*                                                                      343                                          76)   (Fmoc)-Arg-Cys*-(β-Asp)-(Tic)-Cys*                                                                    457                                          77)   (Fmoc)-Arg-Cys*-(β-Asp)-Pro-Cys*-NH.sub.2                                                             163                                          85)   (Fmoc)-Arg-Cys*-(β-Asp)-Cys*                                                                          126                                          86)   (Ac)-Cys*-(β-Asp(OFm))-(ThioP)-Cys*                                                                   86                                           __________________________________________________________________________      .sup.1 IC.sub.50 for adhesion inhibition                                       .sup.2 For detailed description of the tests used see patent body              *denotes residue utilized in the cyclization of the compound                   In Table 3, the amino acid without an indication of enantiomeric structur      means Lenantiomer.                                                        

We claim:
 1. A compound of the formula (I): ##STR19## or a pharmaceutically acceptable salt thereof, wherein L¹ is selected from the group consisting of a residue of an amino acid and an amino acid mimetic, having a functional group suitable for the formation of a cyclizing moiety or bond, Z, between L¹ and L² ;L² is selected from the group consisting of a residue of an amino acid and an amino acid mimetic, having a functional group suitable for the formation of a cyclizing moiety or bond, Z, between L¹ and L² ; Z is a cyclizing moiety or bond between L¹ and L² ; X⁰ is selected from the group consisting of a residue of an amino acid and an amino acid mimetic; r is an integer of 0 or 1; X¹ is selected from the group consisting of a residue of an amino acid and an amino acid mimetic; m is an integer of 0, 1 or 2; X² is selected from the group consisting of β-Asp, β-Asp(R³), γ-Glu and γ-Glu(R³), wherein R³ is selected from the group consisting of --OR, --NHR and --NRR, wherein R is selected from the group consisting of a hydrogen atom, a lower alkyl, an aryl, an arylalkyl, a cycloalkyl, a heteroaryl-lower alkyl and a heterocyclic group; X³ is selected from the group consisting of Ser(R⁴), Thr(R⁴), Tyr(R⁴), Ala, Gly, Lys(R⁴), Orn(R⁴), Dpr(R⁴), N-Me-Ala, Aib, Val, Tic, o-halo-Tyr, m-halo-Tyr, dihalo-Tyr, p-halo-Phe, dihalo-Phe, Sar, Leu, Ile, Nle and Cys(R⁴), wherein when X³ is Ser(R⁴), Thr(R⁴) or Tyr(R⁴), then R⁴ is a substituent of the side chain hydroxyl group of X³ and is selected from the group consisting of a hydrogen atom, a lower alkyl, a cycloalkyl, a cycloalkyl-lower alkanoyl, an aryl, an arylalkyl, an aryloxycarbonyl, an arylcarbonyl, a heteroaryl-lower alkyl, an arylacetyl, a heterocyclic group, a lower alkanoyl or an arylalkoxycarbonyl, when X³ is Lys(R⁴), Orn(R⁴) or Dpr(R⁴), then R⁴ is a substituent of the side chain terminal amino group of X³ and is selected from the group consisting of a hydrogen atom, lower alkyl, a cycloalkyl, a lower alkanoyl, an arylalkyl, an arylalkoxycarbonyl, an aryl, an aryloxycarbonyl, an arylcarbonyl, an arylacetyl, a cycloalkyl-lower alkanoyl, when X³ is Cys(R⁴), then R⁴ is a substituent of the side chain sulfhydryl group of X³ and is selected from the group consisting of a hydrogen atom, lower alkyl, an arylalkyl, an aryl, a cycloalkyl, an aryloxycarbonyl, an arylcarbonyl, an acetamido-lower alkyl, an arylacetyl or a heterocyclic group, lower alkanoyl, an arylalkoxycarbonyl, a cycloalkyl-lower alkanoyl; p is an integer of 0 or 1; X⁴ is selected from the group consisting of Pro, ThioP, Aib, TTC, Asn, TCA, Sar, an N-methylated natural amino acid, Tic and pipecolinic acid; q is an integer of 0 or 1; X⁵ is a residue of an amino acid or an amino acid mimetic; n is an integer of 0, 1, 2 or 3; X⁶ is selected from the group consisting of a residue of an amino acid and an amino acid mimetic; s is an integer of 0 or 1; and R¹ is selected from the group consisting of a hydrogen atom, Xan, Fmoc, 9-FAc, 9-FCA, 1-FCA, Ac, 2-NaphAc, Ada, 5-Finc, biotinyl, Su, 1-NaphCA, For, 1-NaphAc, PhAc, 1-NaphSO₂, 2-NaphSO₂ and 2-NphCA, with the proviso that the compound (Fmoc)-Arg-Cys*-(β-Asp)-(ThioP)-Cys* is excluded.
 2. A compound of claim 1, wherein X⁰ is Trp and X¹ is side chain-protected basic amino acid residue having a side chain terminal amino group with the formula --NHR², where R² is selected from the group consisting of a hydrogen atom, PhAc, 1-NaphAc, 2-NaphAc, Ada, 2-norbornylacetyl, 1-FCA, CHAc and For.
 3. A compound of claim 1, wherein the α-carboxyl group of X² has the formula --C(O)R³, where R³ is selected from the group consisting of --OR, --NHR and --NRR; and R is selected from the group consisting of a hydrogen atom, a lower alkyl, an aryl, a cycloalkyl, a heteroaryl-lower alkyl, a heterocyclic group and an arylalkyl.
 4. A compound of claim 3, wherein R is selected from the group consisting of Fm, methyl, benzyl, cyclohexyl, isobutyl, 1-naphthylmethyl, 2-naphthylmethyl, 1-adamantyl, 2-picolyl, 3-picolyl and, 4-picolyl.
 5. A compound of claim 1, wherein X³ is selected from the group consisting of Ser(R⁴), Thr(R⁴) and Tyr(R⁴); R⁴ is a substituent of the side chain hydroxyl group of X³ and is selected from the group consisting of a hydrogen atom, a lower alkyl, a cycloalkyl, an aryl, a cycloalkyl-lower alkanoyl, an aryloxycarbonyl, an arylcarbonyl, a heteroaryl-lower alkyl, an arylacetyl, a heterocyclic group, a lower alkanoyl, an arylalkoxycarbonyl and an arylalkyl.
 6. A compound of claim 5, wherein R⁴ is selected from the group consisting of methyl, benzyl, cyclohexyl, 1-naphthylmethyl, 2-naphthylmethyl, Fm, 2-picolyl, 3-picolyl, 4-picolyl and isobutyl.
 7. A compound of claim 1, wherein X³ is selected from the group consisting of Lys(R⁴), Orn(R⁴) and Dpr(R⁴), where R⁴ is a substituent of the side chain terminal amino group of X³ and is selected from the group consisting of a hydrogen atom, a lower alkyl, an aryl, a cycloalkyl, a lower alkanoyl, an arylalkyl, an arylalkoxycarbonyl, an aryloxycarbonyl, an arylcarbonyl, an arylacetyl and a cycloalkyl-lower alkanoyl.
 8. A compound of claim 7, wherein R⁴ is selected from the group consisting of cyclohexyl, 1-naphthylmethyl, 2-naphthylmethyl, Fmoc, 1-FCA, 9-FCA, Ada, Ac and 9-FAc.
 9. A compound of claim 1, wherein X⁵ and/or X⁶ is a side chain-protected derivative of a basic amino acid residue having a side chain terminal amino group with the formula --NHR⁴, where R⁴ is selected from the group consisting of a hydrogen atom, a lower alkyl, an aryl, a cycloalkyl, a cycloalkyl-lower alkanoyl, an arylalkyl, an arylalkoxycarbonyl, a lower alkanoyl, a heterocyclic group, an aryloxycarbonyl, an arylcarbonyl and an arylacetyl.
 10. A compound of claim 9, wherein R⁴ is selected from the group consisting of Ada, cyclohexyl, 1-naphthylmethyl, 2-naphthylmethyl, Ac, Fmoc, 9-FAc, 9-FCA and 1-FCA.
 11. A compound of claim 1, wherein X⁵ and/or X⁶ is a side chain-protected derivative of an acidic amino acid residue having a side chain terminal carboxyl group with the formula --C(O)R⁴, where R⁴ is selected from the group consisting of --OR, --NHR and --NRR; and R is selected from the group consisting of a hydrogen atom, a lower alkyl, a cycloalkyl, a heteroaryl-lower alkyl, a heterocyclic group, an aryl and an arylalkyl.
 12. A compound of claim 11, wherein R is selected from the group consisting of Fm, methyl, isobutyl, benzyl, cyclohexyl, 1-naphthylmethyl, 2-naphthylmethyl, 2-picolyl, 3-picolyl, 4-picolyl and 1-adamantyl.
 13. A compound of claim 1, wherein X⁵ and/or X⁶ is selected from the group consisting of Ser(R⁴), Thr(R⁴), Tyr(R⁴) and side-chain hydroxyl containing synthetic amino acids; R⁴ is a substituent of the side hydroxyl groups of X⁵ and/or X⁶ and R⁴ is selected from the group consisting of a hydrogen atom, a lower alkyl, a cycloalkyl, a heteroaryl-lower alkyl, an aryloxycarbonyl, an arylcarbonyl, an arylacetyl, a heterocyclic group, an aryl, an arylalkyl, a cycloalkyl-lower alkanoyl, a lower alkanoyl and an arylalkoxycarbonyl.
 14. A compound of claim 13, wherein R⁴ is selected from the group consisting of Fm, methyl, isobutyl, benzyl, cyclohexyl, 1-naphthylmethyl, 2-naphthylmethyl, 2-picolyl, 3-picolyl and 4-picolyl.
 15. A compound of claim 1, wherein X³ and/or X⁵ and/or X⁶ is selected from the group consisting of Cys(R⁴) and sulfhydryl side-chain containing synthetic amino acids; R⁴ is a substituent of the side chain sulfhydryl group of X⁵ and/or X⁶ and R⁴ is selected from the group consisting of a hydrogen atom, a lower alkyl, an aryl, a cycloalkyl, an acetamido-lower alkyl, an aryloxycarbonyl, an arylcarbonyl, an arylacetyl, a cycloalkyl-lower alkanoyl, a heterocyclic group, an arylalkyl, a lower alkanoyl and an arylalkoxycarbonyl.
 16. A compound of claim 15, wherein R⁴ is selected from the group consisting of methyl, benzyl, Fm, cyclohexyl, 1-naphthylmethyl, 2-naphthylmethyl, Acm, 4-methylbenzyl and Ada.
 17. A compound of claim 1, wherein the C-terminal α-carboxyl group has the formula --C(O)R⁵, where R⁵ is selected from the group consisting of --OR, --NHR and --NRR and R is selected from the group consisting of a hydrogen atom, a lower alkyl, an aryl, a cycloalkyl, a heteroaryl-lower alkyl, a heterocyclic group and an arylalkyl.
 18. A compound of claim 17, wherein R is selected from the group consisting of Fm, benzyl, cyclohexyl, 1-naphthylmethyl, 2-naphthylmethyl, methyl, isobutyl, 2-picolyl, 3-picolyl, 4-picolyl and 1-adamantyl.
 19. A compound of claim 1, wherein L¹ is selected from the group consisting of Cys, Arg, Pen, Orn, Lys, Dpr, Gly, Met, Glu and Asp, provided that when X⁰ or X¹ is present, L¹ is not Arg or Gly;L² is selected from the group consisting of Cys, Cys--NH₂, Pen, Orn, Lys, Dpr, Met, Glu and Asp, provided that when X⁵ or X⁶ is present, L² is not Cys--NH₂ ; Z is selected from a single bond, a lower alkylene or a group of the formula: --COCH₂ --; X⁰ is selected from the group consisting of Trp, 1-Nal, 2-Nal, Tyr, Leu, Nle, Ile, Val, NorVal and Cha; X¹ is selected from the group consisting of Lys(R²), Gly, Nα-Me-Arg, Nle, Cha, Val, NorVal, Dpr(R²), Arg, Orn(R²), Leu, Ile and Abu; R² is selected from a hydrogen atom, Ada, 2-norbornylacetyl, 1-FCA, 1-NaphAc, 2-NaphAc, PhAc, For or CHAc; X² is selected from the group consisting of β-Asp and β-Asp(R³), γ-Glu and γ-Glu(R³) and R³ is --OR, --NHR or --NRR and where R is a hydrogen atom, a lower alkyl, an aryl, an arylalkyl, cycloalkyl, a heteroaryl-lower alkyl or heterocyclic group; and X⁵ and/or X⁶ is selected from the group consisting of Ala; Asp(R⁴) and Glu(R⁴) wherein R⁴ is a substituent of the derivatized side chain terminal carboxyl group and is selected from the group consisting of --OR, --NRR and --NHR where R is selected from the group consisting of a hydrogen atom, a lower alkyl, an aryl, a cycloalkyl, a heteroaryl-lower alkyl, a heterocyclic group and an arylalkyl; Ser(R⁴), Tyr(R⁴) and Thr(R⁴) wherein R⁴ is a substituent of the derivatized side chain hydroxyl group and is selected from the group consisting of H, a lower alkyl, a cycloalkyl, an aryl and an arylalkyl; Gly; Abu; Lys(R⁴); Dpr(R⁴) and Orn(R⁴) wherein R⁴ is a substituent of the derivatized side chain terminal amino group and is selected from the group consisting of H, a lower alkyl, a cycloalkyl, a lower alkanoyl, an aryl alkyl, an arylalkoxycarbonyl, an aryl, an aryloxycarbonyl, an arylcarbonyl and an arylacetyl; AnC; Leu; Val; Ile; Nle; β-Ala and Cys(R⁴) wherein R⁴ is a substituent of the derivatized side chain sulfhydryl group and is selected from the group consisting of a lower alkyl, a cycloalkyl, an acetamido-lower alkyl, an aryl and an arylalkyl.
 20. A compound of claim 19, wherein R¹ is selected from the group consisting of hydrogen, Xan, 9-FAc, 9-FCA, 1-FCA, Ac, 2-NaphAc, Ada, 5-Finc, biotinyl, Su, 1-NaphCA, For, 1-NaphAc, PhAc, 1-NaphSO₂, 2-NaphSO₂ and 2-NaphCA.
 21. A compound of claim 19, wherein p is an integer of
 1. 22. A compound of claim 1, wherein Z is selected from a single bond, a lower alkylene or a group of the formula: --COCH₂ --;R¹ is selected from hydrogen, 1-FCA, 9-FAc, Ada, 5-Finc, Ac, Biotinyl, 9-FCA, Fmoc, For, 9-FAc, 2-NaphAc, PhAc, 1-NaphSO₂, 2-NaphSO₂, 2-NaphCA or Xan; X⁰ is Trp; r is an integer of 0 or 1; X¹ is selected from Arg, Nu-Me-Arg, Lys, Lys(Ada), Lys(1-NaphAc), Lys(PhAc), Lys(For), Lys(2-NaphAc), Orn, Orn(PhAc), Gly, Nle or Cha; m is an integer of 0 or 1; L¹ is selected from Cys, Lys or Pen; X² is selected from β-Asp or β-Asp(αOFm); X³ is selected from Ser, N-Me-Ala, Gly or Ala; X⁴ is selected from ThioP, Asn, TCA, Pro, Aib or Tic; L² is selected from Cys, Cys--NH₂, Asp or Pen; X⁵ is selected from Ala, Gly, Abu or Lys(Fmoc); and X⁶ is selected from Asp-(OFm), Asp-(NH-Ada), Ser, Lys, Lys(Fmoc)--NH₂ or Gly.
 23. A compound of claim 22, wherein R¹ is selected from hydrogen, 1-FCA, 9-FAc, Ada, 5-Finc, Ac, Biotinyl, 9-FCA, For, 9-FAc, 2-NaphAc, PhAc, 1-NaphSO₂, 2-NaphSO₂, 2-NaphCA or Xan.
 24. A compound of claim 23, wherein:Z is a single bond; R¹ is selected from 1-FCA, 9-FAc, Ac or Xan; r is an integer of 0; X¹ is selected from Arg or Lys; m is an integer of 1; L¹ is Cys; X² is β-Asp; p is an integer of 0; X⁴ is ThioP; q is an integer of 1; L² is selected from Cys or Cys--NH₂ ; n is an integer of 0; and s is an integer of
 0. 25. A compound of the formula: ##STR20## wherein R¹ is a substituent of the α-amino group of Arg and is selected from the group consisting of 9-FCA, 1-FCA, 9-FAc, Xan, For, Ac, H, Ada, 5-Finc, PhAc, Su and biotinyl.
 26. A compound of the formula: ##STR21## wherein R¹ is a substituent of the α-amino group of Lys and is selected from the group consisting of 9-FCA, Fmoc, 1-FCA and 9-FAc.
 27. A compound of the formula: ##STR22## wherein R¹ is a substituent of the α-amino group of Lys and is selected from the group consisting of Fmoc, 9-FCA, and 1-FCA; and the ε-amino terminal group of Lys is denoted as NHR² where R² is selected from the group consisting of 1-NaphAc, 2-NaphAc, H, For and PhAc.
 28. A compound of the formula: ##STR23## wherein R¹ is a substituent of the α-amino group of Arg and is selected from the group consisting of 2-NaphAc, 9-FCA, 1-FCA, 2-NaphCA, Ac, PhAc, 1-NaphSO₂ and 2-NaphSO₂.
 29. A compound of the formula: ##STR24## wherein R¹ is a substituent of the α-amino group of Lys and is selected from the group consisting of 9-FCA and 1-FCA; and the ε-amino terminal group of Lys is denoted as NHR², where R² is H, 1-NaphAc, 2-NaphAc or PhAc.
 30. A compound of the formula: ##STR25##
 31. A compound of the formula ##STR26##
 32. A compound of the formula ##STR27## wherein R¹ is a substituent of the α-amino group of Lys and is selected from the group consisting of Fmoc, 9-FAc, 9-FCA and 1-FCA; and the ε-amino terminal group of Lys is denoted as NHR², where R² is selected from the 25 group consisting of H, 1-NaphAc, 2-NaphAc and PhAc.
 33. A compound of the formula: ##STR28## wherein R¹ is a substituent of the α-amino group of Arg and is selected from the group consisting of Fmoc, 9-FCA, 1-FCA and 9-FAc.
 34. A compound of the formula: ##STR29## wherein R¹ is a substituent of the α-amino group of Arg and is selected from the group consisting of Fmoc, 9-FCA, 1-FCA and 9-FAc.
 35. A compound of the formula: ##STR30## wherein R¹ is a substituent of the α-amino group of Arg and is selected from the group consisting of 1-FCA, 9-FCA, 9-FAc, and Fmoc.
 36. A compound of the formula: ##STR31## wherein R¹ is a substituent of the α-amino group of Arg and is selected from the group consisting of 1-FCA, 9-FCA, 9-FAc, and Fmoc.
 37. A compound of the formula: ##STR32## wherein R¹ is a substituent of the α-amino group of Orn and is selected from the group consisting of 1-FCA and Fmoc; and the side chain terminal amino group of Orn is denoted as NHR², where R² is selected from the group consisting of H and PhAc.
 38. A compound selected from the group consisting of(9-FCA)-Arg-Cys*-(β-Asp)-(N-Me-Ala)-Cys*, (1-FCA)-Arg-Cys*-(β-Asp)-Ser-(ThioP)-Cys*, (1-FCA)-Arg-Cys*-(β-Asp)-Ser-(ThioP)-Cys*-Ala-Ala, (1-NaphSO₂)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Ala, (2-NaphSO₂)-Arg-Cys*-(β-Asp)-(ThioP)-Cys*-Ala-Ala, (1-FCA)-Arg-Cys*-(β-Asp)-(TCA)-Cys*, (Fmoc)-Arg-Cys*-(β-Asp)-(Aib)-Cys*, (Fmoc)-Arg-Cys*-(β-Asp)-(N-Me-Ala)-Cys*, (Fmoc)-Arg-Cys*-(β-Asp)-(N-Me-Ala)-Cys*-NH₂ and (Ac)-Cys*-(β-Asp)(αOFm)-(ThioP)-Cys*.
 39. A pharmaceutical composition comprising: the compound of claim 1, and a pharmaceutically acceptable carrier.
 40. A compound according to claim 1, wherein r=0, m=1, and X¹ is Arg or Lys.
 41. A compound according to claim 40, wherein R¹ is selected from the group consisting of Xan, 2-NaphAc, 9-FCA, 1-FCA, 2-NaphCA, Ac, PhAc, 1-NaphSO₂ and 2-NaphSO₂.
 42. A compound according to claim 1, whereinr is 0; X¹ is selected from the group consisting of a residue of an amino acid and a residue of an amino acid mimetic; m is 1; and X² is selected from the group β-Asp, β-Asp(R³), γ-Glu and γ-Glu(R³), wherein R³ is selected from the group consisting of --OR, --NHR and --NRR, wherein R is selected from the group consisting of a hydrogen atom, a lower alkyl, an aryl, an arylalkyl, a cycloalkyl a heteroaryl-lower alkyl and a heterocyclic group.
 43. A compound according to claim 42, wherein p is 0, q is 1 and X⁴ is selected from the group consisting of Pro, ThioP, Aib, TTC, Asn, TCA, Sar, an N-methylated natural amino acid, Tic and pipecolinic acid.
 44. A compound according to claim 43, wherein r=0, m=1, and X¹ is Arg or Lys.
 45. A compound according to claim 42, 43 or 44, wherein R¹ is selected from the group consisting of Xan, 2-NaphAc, 9-FCA, 1-FCA, 2-NaphCA, Ac, PhAc, 1-NaphSO₂ and 2-NaphSO₂. 